Documentation warnings from pandoc resolved

Diagrams in API documentation

.gitignore

@@ -1,6 +1,5 @@
-.*/
-vendor
+vendor/
 .*.cache/
-*.phar
 .phpdoc/
-output/
+output/
+tools/

.phive/phars.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phive xmlns="https://phar.io/phive">
+  <phar name="phpmd" version="^2.15.0" installed="2.15.0" location="./tools/phpmd" copy="false"/>
+  <phar name="phpstan" version="^2.1.12" installed="2.1.32" location="./tools/phpstan" copy="false"/>
+  <phar name="psalm" version="^7.0.0-beta6" installed="7.0.0-beta11" location="./tools/psalm" copy="false"/>
+  <phar name="phpcs" version="^3.12.2" installed="3.13.5" location="./tools/phpcs" copy="false"/>
+  <phar name="phpcbf" version="^3.12.2" installed="3.13.5" location="./tools/phpcbf" copy="false"/>
+  <phar name="phpdocumentor" version="^3.7.1" installed="3.9.1" location="./tools/phpdocumentor" copy="false"/>
+  <phar name="phpbench" version="^1.4.1" installed="1.4.3" location="./tools/phpbench" copy="false"/>
+  <phar name="infection" version="^0.29.14" installed="0.29.14" location="./tools/infection" copy="false"/>
+  <phar name="phpunit" version="^12.1.3" installed="12.4.4" location="./tools/phpunit" copy="false"/>
+</phive>

.phpcs.xml

@@ -6,6 +6,11 @@
     <file>tests/</file>
     <file>benchmark/</file>
 
+    <arg name="basepath" value="."/>
+    <arg name="colors"/>
+    <arg name="parallel" value="8"/>
+    <arg name="report" value="emacs"/>
+    <arg value="p"/>
 
     <rule ref="PSR1">
         <exclude name="Generic.Files.LineLength"/>
@@ -18,23 +23,19 @@
         <exclude name="Generic.Files.LowercasedFilename.NotFound"/>
         <exclude name="Generic.PHP.ClosingPHPTag.NotFound"/>
         <exclude name="Generic.Files.EndFileNoNewline.Found"/>
-        <exclude name="Generic.Files.EndFileNoNewline.Found"/>
         <exclude name="Generic.Arrays.DisallowShortArraySyntax.Found"/>
         <exclude name="Generic.Functions.OpeningFunctionBraceKernighanRitchie.BraceOnNewLine"/>
         <exclude name="Generic.Classes.OpeningBraceSameLine.BraceOnNewLine"/>
         <exclude name="Generic.PHP.LowerCaseConstant.Found"/>
-        <exclude name="Generic.Formatting.SpaceAfterCast"/>
         <exclude name="Generic.Formatting.MultipleStatementAlignment.NotSameWarning"/>
         <exclude name="Generic.Commenting.DocComment.MissingShort"/>
         <exclude name="Generic.NamingConventions.AbstractClassNamePrefix.Missing"/>
         <exclude name="Generic.CodeAnalysis.ForLoopWithTestFunctionCall.NotAllowed"/>
         <exclude name="Generic.NamingConventions.InterfaceNameSuffix.Missing"/>
-        <exclude name="Generic.Commenting.Todo.TaskFound"/>
         <exclude name="Generic.CodeAnalysis.UnusedFunctionParameter.FoundInImplementedInterfaceAfterLastUse"/>
         <exclude name="Generic.CodeAnalysis.UnusedFunctionParameter.FoundInExtendedClassAfterLastUsed"/>
         <exclude name="Generic.CodeAnalysis.UnusedFunctionParameter.FoundInImplementedInterfaceAfterLastUsed"/>
-        <exclude name="Generic.Formatting.SpaceBeforeCast.NoSpace"/>
-        <exclude name="Generic.CodeAnalysis.UselessOverridingMethod.Found"/>
+        
         <exclude name="Squiz.Functions.MultiLineFunctionDeclaration.NewlineBeforeOpenBrace"/>
     </rule>
 
@@ -50,4 +51,25 @@
             </property>
         </properties>
     </rule>
+
+    <rule ref="Generic.Formatting.SpaceAfterCast">
+        <properties>
+            <property name="spacing" value="0"/>
+        </properties>
+    </rule>
+
+    <!-- Do not allow unreachable code. -->
+    <rule ref="Squiz.PHP.NonExecutableCode"/>
+
+    <!-- Do not allow ambiguous conditions. -->
+    <rule ref="Generic.CodeAnalysis.RequireExplicitBooleanOperatorPrecedence"/>
+
+    <!-- The testing bootstrap file uses string concats to stop IDEs seeing the class aliases -->
+    <rule ref="Generic.Strings.UnnecessaryStringConcat" />
+
+    <!-- This test file specifically *needs* Windows line endings for testing purposes. -->
+    <rule ref="Generic.Files.LineEndings.InvalidEOLChar" />
+
+    <!-- Avoid false positive with this sniff detecting itself -->
+    <rule ref="Generic.Commenting.Todo"/>
 </ruleset>

.phplint.yml

@@ -1,12 +0,0 @@
-path:
-  - src/
-  - tests/
-  - benchmark/
-jobs: 10
-extensions:
-  - php
-exclude:
-  - vendor
-warning: true
-memory-limit: -1
-log-junit: "output/lint.xml"

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "php.version": "8.4"
+}

.woodpecker/test.yml

@@ -1,3 +1,5 @@
+when:
+  - event: [push, tag]
 steps:
   - name: requirements
     image: composer
@@ -8,7 +10,7 @@ steps:
     commands:
       - php examples/3teams.php
       - php examples/basic.php
-  - name: dependencies
+  - name: test
     image: composer
     commands:
     - composer install

README.md

@@ -1,5 +1,6 @@
 ---
 title: README
+lang: en
 ...
 # PHP TrueSkill Implementation
 This is a PHP port of the Moserware.Skills project that's available at

benchmark/BasicBench.php

@@ -10,9 +10,11 @@ use DNW\Skills\TrueSkill\FactorGraphTrueSkillCalculator;
 use DNW\Skills\GameInfo;
 use DNW\Skills\Player;
 use DNW\Skills\Team;
-use DNW\Skills\Teams;
 
-class BasicBench
+/**
+ * Basic Benchmarks.
+ */
+final class BasicBench
 {
     /**
      * To benchmark performance when using TwoPlayerTrueSkillCalculator
@@ -39,9 +41,11 @@ class BasicBench
 
             $team1 = new Team($p1, $newRatings->getRating($p1));
             $team2 = new Team($p2, $newRatings->getRating($p2));
-
-            $newRatings->getRating($p1)->getConservativeRating();
-            $newRatings->getRating($p2)->getConservativeRating();
+            
+            ob_start();
+            echo $newRatings->getRating($p1)->getConservativeRating();
+            echo $newRatings->getRating($p2)->getConservativeRating();
+            ob_clean();
         }
     }
 
@@ -71,8 +75,10 @@ class BasicBench
             $team1 = new Team($p1, $newRatings->getRating($p1));
             $team2 = new Team($p2, $newRatings->getRating($p2));
 
-            $newRatings->getRating($p1)->getConservativeRating();
-            $newRatings->getRating($p2)->getConservativeRating();
+            ob_start();
+            echo $newRatings->getRating($p1)->getConservativeRating();
+            echo $newRatings->getRating($p2)->getConservativeRating();
+            ob_clean();
         }
     }
 
@@ -102,8 +108,10 @@ class BasicBench
             $team1 = new Team($p1, $newRatings->getRating($p1));
             $team2 = new Team($p2, $newRatings->getRating($p2));
 
-            $newRatings->getRating($p1)->getConservativeRating();
-            $newRatings->getRating($p2)->getConservativeRating();
+            ob_start();
+            echo $newRatings->getRating($p1)->getConservativeRating();
+            echo $newRatings->getRating($p2)->getConservativeRating();
+            ob_clean();
         }
     }
 
@@ -136,9 +144,11 @@ class BasicBench
             $team2 = new Team($p2, $newRatings->getRating($p2));
             $team3 = new Team($p3, $newRatings->getRating($p3));
 
-            $newRatings->getRating($p1)->getConservativeRating();
-            $newRatings->getRating($p2)->getConservativeRating();
-            $newRatings->getRating($p3)->getConservativeRating();
+            ob_start();
+            echo $newRatings->getRating($p1)->getConservativeRating();
+            echo $newRatings->getRating($p2)->getConservativeRating();
+            echo $newRatings->getRating($p3)->getConservativeRating();
+            ob_clean();
         }
     }
 }

composer.json

@@ -1,16 +1,19 @@
 {
   "name": "dnw/php-trueskill",
-  "description": "Trueskill implementation by Moserware updated for PHP 8.2",
-  "keywords": ["trueskill", "matchmaking", "ranking", "skill", "elo"],
+  "description": "Trueskill implementation by Moserware updated for PHP 8.4",
+  "keywords": [
+    "trueskill",
+    "matchmaking",
+    "ranking",
+    "skill",
+    "elo"
+  ],
   "require": {
-    "php": "^8.2"
+    "php": "^8.4"
   },
   "require-dev": {
-    "phpstan/phpstan": "^1.0",
-    "vimeo/psalm": "^5.21.1",
     "phpmetrics/phpmetrics": "^3.0-dev",
-    "phpunit/phpunit": "^10.5",
-    "psalm/plugin-phpunit": "^0.18.4",
+    "phpunit/phpunit": "^11.2",
     "rector/rector": "^1.0",
     "league/csv": "^9.0"
   },
@@ -25,33 +28,36 @@
     }
   },
   "scripts": {
-    "test":          "phpunit",
-    "document":      "phpDocumentor", 
-    "benchmark":     "phpbench run --report=default --output=build-artifact",
-    "metrics":       "vendor/bin/phpmetrics --config=phpmetrics.json",
+    "test": "tools/phpunit",
+    "document": "tools/phpdocumentor",
+    "benchmark": "tools/phpbench run --report=default --output=build-artifact",
+    "metrics": "phpmetrics --config=phpmetrics.yml",
     "lint": [
-        "phplint",
-        "phpcs"
+      "tools/phpcbf",
+      "tools/phpcs",
+      "tools/phpmd src/,tests/,benchmark/,examples/ text phpmd.ruleset.xml"
     ],
     "analyze": [
-        "@analyze-phpstan",
-        "@analyze-psalm",
-        "@analyze-rector"
+      "@analyze-phpstan",
+      "@analyze-psalm",
+      "@analyze-rector"
     ],
-    "analyze-phpstan":"vendor/bin/phpstan analyze --error-format=raw",
-    "analyze-psalm":  "vendor/bin/psalm --no-cache --show-info=true",
-    "analyze-rector": "vendor/bin/rector --dry-run",
+    "analyze-phpstan": "tools/phpstan analyze --error-format=raw",
+    "analyze-psalm": "tools/psalm --show-info=true",
+    "analyze-rector": "rector --dry-run",
     "html": [
-      "pandoc -s README.md -o output/README.html",
-      "pandoc -s docs/index.rst -o output/index.html"
+      "pandoc --verbose -s README.md -o output/README.html",
+      "pandoc --verbose -f rst -s docs/index.rst -o output/index.html --metadata=lang:en",
+      "tools/phpcs --generator=MarkDown | pandoc --verbose -f markdown -s -o output/CodeStandard.html --metadata title='Code Standard' --metadata=lang:en"
     ],
     "all": [
       "@test",
-      "@document",
-      "@benchmark",
       "@lint",
       "@analyze",
+      "@document",
+      "@metrics",
       "@html"
     ]
-  }
+  },
+  "type": "library"
 }

docs/index.rst

@@ -1,5 +1,7 @@
+=============
 Documentation
 =============
+
 This is a PHP port of the Moserware.Skills project that's available at
 
 http://github.com/moserware/Skills
@@ -17,9 +19,9 @@ https://www.moserware.com/2010/03/computing-your-skill.html
 
 From Microsoft
 --------------
-The TrueSkill ranking system is a skill based ranking system for Xbox Live(opens in new tab) developed at Microsoft Research(opens in new tab). The purpose of a ranking system is to both identify and track the skills of gamers in a game (mode) in order to be able to match them into competitive matches. TrueSkill has been used to rank and match players in many different games, from Halo 3 to Forza Motorsport 7(opens in new tab).
+The TrueSkill ranking system is a skill based ranking system for Xbox Live developed at Microsoft Research. The purpose of a ranking system is to both identify and track the skills of gamers in a game (mode) in order to be able to match them into competitive matches. TrueSkill has been used to rank and match players in many different games, from Halo 3 to Forza Motorsport 7.
 
-An improved version of the TrueSkill ranking system, named TrueSkill 2(opens in new tab), launched with Gears of War 4(opens in new tab) and was later incorporated into Halo 5(opens in new tab).
+An improved version of the TrueSkill ranking system, named TrueSkill 2, launched with Gears of War 4 and was later incorporated into Halo 5.
 
 The classic TrueSkill ranking system only uses the final standings of all teams in a match in order to update the skill estimates (ranks) of all players in the match. The TrueSkill 2 ranking system also uses the individual scores of players in order to weight the contribution of each player to each team. As a result, TrueSkill 2 is much faster at figuring out the skill of a new player.
 
@@ -30,14 +32,19 @@ Links
 * `Project README <README.html>`_
 * `API Documentations <docs/>`_
 * `CodeCoverage <coverage/>`_
-* `Metrics <metrics/>`_
 * `Test report <test/index.html>`_
-* `Mutation testing <mutation/>`_
+* `Mutation testing <mutation/infection.html>`_
+* `Code metrics <metrics/index.html>`_
+* `Code Standard <CodeStandard.html>`_
+* `Benchmark <benchmark.html>`_
 
 
 Standard Tools
 --------------
-* PHP8.3
+* PHP8.4
+
+Development Tools
+-------------------
 * PlantUML
 * GraphViz
 * Pandoc
@@ -47,7 +54,5 @@ PHP Tools
 ---------
 For development Composer and the following packages are used (Recommended as Phars installed via Phive)
 
-* sudo phive install -g composer phpdocumentor infection phpcs phpcbf phploc phpbench 
-* sudo phive install -g overtrue/phplint --force-accept-unsigned
 * composer install
 * composer all

examples/3teams.php

@@ -20,7 +20,7 @@ $team2 = new Team($p2, $gameInfo->getDefaultRating());
 $team3 = new Team($p3, $gameInfo->getDefaultRating());
 
 
-for($i = 0; $i < 5; ++$i) {
+for ($i = 0; $i < 5; ++$i) {
     echo "Iteration: " . $i . PHP_EOL;
     $teams = [$team1, $team2, $team3];
 
@@ -32,10 +32,7 @@ for($i = 0; $i < 5; ++$i) {
     $team2 = new Team($p2, $newRatings->getRating($p2));
     $team3 = new Team($p3, $newRatings->getRating($p3));
 
-    echo "P1: ". $newRatings->getRating($p1)->getConservativeRating() . PHP_EOL;
-    echo "P2: ". $newRatings->getRating($p2)->getConservativeRating() . PHP_EOL;
-    echo "P3: ". $newRatings->getRating($p3)->getConservativeRating() . PHP_EOL;
+    echo "P1: " . $newRatings->getRating($p1)->getConservativeRating() . PHP_EOL;
+    echo "P2: " . $newRatings->getRating($p2)->getConservativeRating() . PHP_EOL;
+    echo "P3: " . $newRatings->getRating($p3)->getConservativeRating() . PHP_EOL;
 }
-
-
-

examples/basic.php

@@ -19,7 +19,7 @@ $team1 = new Team($p1, $gameInfo->getDefaultRating());
 $team2 = new Team($p2, $gameInfo->getDefaultRating());
 
 
-for($i = 0; $i < 5; ++$i) {
+for ($i = 0; $i < 5; ++$i) {
     echo "Iteration: " . $i . PHP_EOL;
     $teams = [$team1, $team2];
 
@@ -30,9 +30,6 @@ for($i = 0; $i < 5; ++$i) {
     $team1 = new Team($p1, $newRatings->getRating($p1));
     $team2 = new Team($p2, $newRatings->getRating($p2));
 
-    echo "P1: ". $newRatings->getRating($p1)->getConservativeRating() . PHP_EOL;
-    echo "P2: ". $newRatings->getRating($p2)->getConservativeRating() . PHP_EOL;
+    echo "P1: " . $newRatings->getRating($p1)->getConservativeRating() . PHP_EOL;
+    echo "P2: " . $newRatings->getRating($p2)->getConservativeRating() . PHP_EOL;
 }
-
-
-

examples/motogp/goat.php

@@ -0,0 +1,91 @@
+<?php
+
+require __DIR__ . "/../../vendor/autoload.php";
+
+use League\Csv\Reader;
+use League\Csv\Statement;
+use DNW\Skills\TrueSkill\FactorGraphTrueSkillCalculator;
+use DNW\Skills\GameInfo;
+use DNW\Skills\Player;
+use DNW\Skills\Team;
+use DNW\Skills\Teams;
+
+//load the CSV document from a stream
+$csv = Reader::createFromPath('motogp.csv', 'r');
+$csv->setDelimiter(',');
+$csv->setHeaderOffset(0);
+$csv->setEscape('');
+
+//build a statement
+$statement = new Statement();
+$stmt = $statement->where(static fn (array $record): bool => $record['category'] == "MotoGP" ||  $record['category'] == "500cc");
+
+/**
+ * @var $riders Player[]
+ */
+$riders = [];
+//query your records from the document
+$records = $stmt->process($csv);
+
+$gameInfo = new GameInfo();
+$calculator = new FactorGraphTrueSkillCalculator();
+$first_record = $records->first();
+$year_race = $first_record['year'] . '_' . $first_record['sequence'] . '_' . $first_record['category'];
+
+$race_rate = [];
+foreach ($records as $record) {
+    if ($year_race !== $record['year'] . '_' . $record['sequence'] . '_' . $record['category']) {
+        //Calculate the old race
+        $newRatings = $calculator->calculateNewRatings($gameInfo, $teams, $pos);
+
+        //update ratings
+        $highest_rate = 0;
+        $highest_rider = "";
+        foreach ($riders as $rider) {
+            //echo $rider['P']->getId().": ". $newRatings->getRating($rider['P'])->getConservativeRating() . PHP_EOL;
+            $rider['T']->setRating($rider['P'], $newRatings->getRating($rider['P']));
+            if ($newRatings->getRating($rider['P'])->getConservativeRating() > $highest_rate) {
+                $highest_rate = $newRatings->getRating($rider['P'])->getConservativeRating();
+                $highest_rider = $rider['P']->getId();
+            }
+        }
+
+        echo sprintf('Highest rider: %s => %s', $highest_rider, $highest_rate) . PHP_EOL;
+
+        foreach ($global_riders as $r) {
+            $rate = $r['T']->getRating($r['P'])->getConservativeRating();
+
+            $race_rate[$year_race][$r['P']->getId()] = $rate;
+            if (! isset($top_rating[$r['P']->getId()]) || $top_rating[$r['P']->getId()] < $rate) {
+                $top_rating[$r['P']->getId()] = $rate;
+            }
+        }
+
+        //prepare for next race
+        $year_race = $record['year'] . '_' . $record['sequence'] . '_' . $record['category'];
+        $races[] = ['year' => $record['year'], 'race' => $record['sequence'], 'circuit' => $record['circuit_name']];
+        echo "New Race: " . $year_race . ' => ' . $record['circuit_name'] . PHP_EOL;
+        $riders = [];
+        $teams = [];
+        $pos = [];
+    }
+
+    //Is it a new rider?
+    if (! isset($global_riders[$record['rider']])) {
+        $global_riders[$record['rider']]['P'] = new Player($record['rider_name']);
+        $global_riders[$record['rider']]['T'] = new Team($global_riders[$record['rider']]['P'], $gameInfo->getDefaultRating());
+        //echo "New Rider: ". $record['rider'] . " => ".$global_riders[$record['rider']]['P']->getId().PHP_EOL;
+    }
+
+    $riders[] = $global_riders[$record['rider']];
+    $teams[] = $global_riders[$record['rider']]['T'];
+    
+    //Position or DNF?
+    $pos[] = $record['position'] >= 1 ? $record['position'] : end($pos);
+}
+
+echo "All time top score" . PHP_EOL;
+asort($top_rating);
+foreach ($top_rating as $n => $r) {
+    echo sprintf('%s => %s', $n, $r) . PHP_EOL;
+}

infection.json5

@@ -1,8 +1,8 @@
 {
-    "$schema": "https://raw.githubusercontent.com/infection/infection/0.27.9/resources/schema.json",
+    "$schema": "https://raw.githubusercontent.com/infection/infection/0.29.6/resources/schema.json",
     "source": {
         "directories": [
-            "src"
+            "src/"
         ]
     },
     "logs": {

phpbench.json

@@ -10,6 +10,5 @@
             "path": "output/benchmark.html",
             "title": "Benchmarking"
         }
-   }
-   
+   }   
 }

phpdoc.xml

@@ -16,5 +16,5 @@
             </source>
         </api>
     </version>
-    <!--setting name="graphs.enabled" value="true"/-->
+    <setting name="graphs.enabled" value="true"/>
 </phpdocumentor>

phpmd.baseline.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<phpmd-baseline>
+  <violation rule="PHPMD\Rule\Design\TooManyPublicMethods" file="src/Numerics/GaussianDistribution.php"/>
+  <violation rule="PHPMD\Rule\UnusedPrivateMethod" file="src/Numerics/GaussianDistribution.php" method="errorFunctionCumulativeTo"/>
+  <violation rule="PHPMD\Rule\UnusedPrivateMethod" file="src/Numerics/GaussianDistribution.php" method="inverseErrorFunctionCumulativeTo"/>
+  <violation rule="PHPMD\Rule\Design\WeightedMethodCount" file="src/Numerics/Matrix.php"/>
+  <violation rule="PHPMD\Rule\Design\CouplingBetweenObjects" file="src/TrueSkill/FactorGraphTrueSkillCalculator.php"/>
+  <violation rule="PHPMD\Rule\Design\CouplingBetweenObjects" file="src/TrueSkill/TrueSkillFactorGraph.php"/>
+</phpmd-baseline>

phpmd.ruleset.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<ruleset name="TrueSkill custom PHPMD rules"
+         xmlns="http://pmd.sf.net/ruleset/1.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0
+                     http://pmd.sf.net/ruleset_xml_schema.xsd"
+         xsi:noNamespaceSchemaLocation="
+                     http://pmd.sf.net/ruleset_xml_schema.xsd">
+    <description>
+        TrueSkill custom PHPMD rules
+    </description>
+
+    <!-- Import the entire unused code rule set -->
+    <rule ref="rulesets/cleancode.xml">
+        <exclude name="StaticAccess" />
+        <exclude name="ElseExpression" />
+    </rule>
+    <rule ref="rulesets/codesize.xml" >
+        <exclude name="TooManyMethods" />
+        <exclude name="TooManyPublicMethods" />
+    </rule>
+    <rule ref="rulesets/codesize.xml/TooManyMethods">
+        <priority>1</priority>
+        <properties>
+            <property name="ignorepattern" value="#^(set|get|test)|test$#i" />
+        </properties>
+    </rule>
+    <rule ref="rulesets/codesize.xml/TooManyPublicMethods">
+        <priority>1</priority>
+        <properties>
+            <property name="ignorepattern" value="#^(set|get|test)|test$#i" />
+        </properties>
+    </rule>
+
+
+    <!--rule ref="rulesets/controversial.xml" /-->
+    <rule ref="rulesets/design.xml" />
+    <rule ref="rulesets/naming.xml" >
+        <exclude name="LongClassName" />
+        <exclude name="ShortClassName" />
+        <exclude name="ShortVariable" />
+        <exclude name="LongVariable" />
+        <exclude name="ShortMethodName" />
+    </rule>
+    <rule ref="rulesets/unusedcode.xml" />
+
+    <!-- Import entire naming rule set and exclude rules -->
+
+</ruleset>

phpmetrics.json

@@ -1,21 +0,0 @@
-{
-    "composer": true,
-    "includes": [
-      "src"
-    ],
-    "excludes": [
-      "tests"
-    ],
-    "report": {
-      "html": "output/metrics/",
-      "json": "output/metrics/report.json"
-    },
-    "plugins": {
-      "git": {
-        "binary": "git"
-      },
-      "junit": {
-        "file": "output/test.xml"
-      }
-    }
-}

phpmetrics.yml

@@ -0,0 +1,18 @@
+---
+composer: true
+includes:
+    - src
+excludes:
+    - benchmark
+    - tests
+extensions:
+    - php
+report:
+  html: "output/metrics/"
+  json: "output/metrics/report.json"
+  violations: "/tmp/violations.xml"
+plugins:
+  git:
+    binary: git
+  junit:
+    file: "output/test.xml"

psalm.xml

@@ -12,11 +12,5 @@
         <directory name="src"/>
         <directory name="tests"/>
         <directory name="benchmark"/>
-        <ignoreFiles>
-            <directory name="vendor"/>
-        </ignoreFiles>
     </projectFiles>
-    <plugins>
-        <pluginClass class="Psalm\PhpUnitPlugin\Plugin"/>
-    </plugins>
 </psalm>

src/FactorGraphs/Factor.php

@@ -15,7 +15,7 @@ abstract class Factor
      */
     private array $messages = [];
 
-    private readonly HashMap $messageToVariableBinding;
+    private readonly HashMap $msgToVariableBinding;
 
     /**
      * @var Variable[] $variables
@@ -24,7 +24,7 @@ abstract class Factor
 
     protected function __construct()
     {
-        $this->messageToVariableBinding = new HashMap();
+        $this->msgToVariableBinding = new HashMap();
     }
 
     /**
@@ -70,7 +70,7 @@ abstract class Factor
     {
         Guard::argumentIsValidIndex($messageIndex, count($this->messages), 'messageIndex');
         $message = $this->messages[$messageIndex];
-        $variable = $this->messageToVariableBinding->getValue($message);
+        $variable = $this->msgToVariableBinding->getValue($message);
 
         return $this->updateMessageVariable($message, $variable);
     }
@@ -85,7 +85,7 @@ abstract class Factor
      */
     public function resetMarginals(): void
     {
-        $allValues = $this->messageToVariableBinding->getAllValues();
+        $allValues = $this->msgToVariableBinding->getAllValues();
         foreach ($allValues as $currentVariable) {
             $currentVariable->resetToPrior();
         }
@@ -101,7 +101,7 @@ abstract class Factor
         Guard::argumentIsValidIndex($messageIndex, count($this->messages), 'messageIndex');
 
         $message = $this->messages[$messageIndex];
-        $variable = $this->messageToVariableBinding->getValue($message);
+        $variable = $this->msgToVariableBinding->getValue($message);
 
         return $this->sendMessageVariable($message, $variable);
     }
@@ -112,7 +112,7 @@ abstract class Factor
 
     protected function createVariableToMessageBindingWithMessage(Variable $variable, Message $message): Message
     {
-        $this->messageToVariableBinding->setValue($message, $variable);
+        $this->msgToVariableBinding->setValue($message, $variable);
         $this->messages[] = $message;
         $this->variables[] = $variable;
 

src/FactorGraphs/FactorGraphLayer.php

@@ -17,14 +17,14 @@ abstract class FactorGraphLayer
     /**
      * @var array<int,array<int,Variable>>
      */
-    private array $outputVariablesGroups = [];
+    private array $outputVarGroups = [];
 
     /**
      * @var array<int,array<int,Variable>>
      */
     private array $inputVariablesGroups = [];
 
-    protected function __construct(private readonly TrueSkillFactorGraph $parentFactorGraph)
+    public function __construct(private readonly TrueSkillFactorGraph $parentFactorGraph)
     {
     }
 
@@ -48,7 +48,7 @@ abstract class FactorGraphLayer
      */
     public function &getOutputVariablesGroups(): array
     {
-        return $this->outputVariablesGroups;
+        return $this->outputVarGroups;
     }
 
     /**

src/FactorGraphs/FactorList.php

@@ -7,7 +7,7 @@ namespace DNW\Skills\FactorGraphs;
 /**
  * Helper class for computing the factor graph's normalization constant.
  */
-class FactorList
+final class FactorList
 {
     /**
      * @var Factor[] $list
@@ -26,16 +26,16 @@ class FactorList
         $listCount = count($this->list);
 
         for ($i = 0; $i < $listCount; ++$i) {
-            $f = $this->list[$i];
+            $factor = $this->list[$i];
 
-            $numberOfMessages = $f->getNumberOfMessages();
+            $numberOfMessages = $factor->getNumberOfMessages();
 
             for ($j = 0; $j < $numberOfMessages; ++$j) {
-                $sumLogZ += $f->sendMessageIndex($j);
+                $sumLogZ += (float)$factor->sendMessageIndex($j);
             }
         }
 
-        $sumLogS = 0;
+        $sumLogS = 0.0;
 
         foreach ($list as &$currentFactor) {
             $sumLogS += $currentFactor->getLogNormalization();

src/FactorGraphs/KeyedVariable.php

@@ -4,7 +4,7 @@ declare(strict_types=1);
 
 namespace DNW\Skills\FactorGraphs;
 
-class KeyedVariable extends Variable
+final class KeyedVariable extends Variable
 {
     public function __construct(private readonly mixed $key, mixed $prior)
     {

src/FactorGraphs/Message.php

@@ -6,7 +6,7 @@ namespace DNW\Skills\FactorGraphs;
 
 use DNW\Skills\Numerics\GaussianDistribution;
 
-class Message
+final class Message
 {
     public function __construct(private GaussianDistribution $value)
     {

src/FactorGraphs/ScheduleLoop.php

@@ -4,12 +4,13 @@ declare(strict_types=1);
 
 namespace DNW\Skills\FactorGraphs;
 
-class ScheduleLoop extends Schedule
+final class ScheduleLoop extends Schedule
 {
     public function __construct(private readonly Schedule $scheduleToLoop, private readonly float $maxDelta)
     {
     }
 
+    #[\Override]
     public function visit(int $depth = -1, int $maxDepth = 0): float
     {
         $delta = $this->scheduleToLoop->visit($depth + 1, $maxDepth);

src/FactorGraphs/ScheduleSequence.php

@@ -4,7 +4,7 @@ declare(strict_types=1);
 
 namespace DNW\Skills\FactorGraphs;
 
-class ScheduleSequence extends Schedule
+final class ScheduleSequence extends Schedule
 {
     /**
      * @param Schedule[] $schedules
@@ -13,6 +13,7 @@ class ScheduleSequence extends Schedule
     {
     }
 
+    #[\Override]
     public function visit(int $depth = -1, int $maxDepth = 0): float
     {
         $maxDelta = 0;

src/FactorGraphs/ScheduleStep.php

@@ -4,12 +4,13 @@ declare(strict_types=1);
 
 namespace DNW\Skills\FactorGraphs;
 
-class ScheduleStep extends Schedule
+final class ScheduleStep extends Schedule
 {
     public function __construct(private readonly Factor $factor, private readonly int $index)
     {
     }
 
+    #[\Override]
     public function visit(int $depth = -1, int $maxDepth = 0): float
     {
         return $this->factor->updateMessageIndex($this->index);

src/FactorGraphs/Variable.php

@@ -10,7 +10,7 @@ class Variable
 {
     private mixed $value;
 
-    public function __construct(private GaussianDistribution $prior)
+    public function __construct(private readonly GaussianDistribution $prior)
     {
         $this->resetToPrior();
     }

src/FactorGraphs/VariableFactory.php

@@ -4,22 +4,22 @@ declare(strict_types=1);
 
 namespace DNW\Skills\FactorGraphs;
 
-class VariableFactory
+final readonly class VariableFactory
 {
-    public function __construct(private \Closure $variablePriorInitializer)
+    public function __construct(private \Closure $varPriorInitializer)
     {
     }
 
     public function createBasicVariable(): Variable
     {
-        $initializer = $this->variablePriorInitializer;
+        $initializer = $this->varPriorInitializer;
 
         return new Variable($initializer());
     }
 
     public function createKeyedVariable(mixed $key): KeyedVariable
     {
-        $initializer = $this->variablePriorInitializer;
+        $initializer = $this->varPriorInitializer;
 
         return new KeyedVariable($key, $initializer());
     }

src/GameInfo.php

@@ -7,30 +7,30 @@ namespace DNW\Skills;
 /**
  * Parameters about the game for calculating the TrueSkill.
  */
-class GameInfo
+final readonly class GameInfo
 {
     /**
      * Default initial mean / 6
      */
-    private const DEFAULT_BETA = 4.1666666666666666666666666666667;
+    private const float DEFAULT_BETA = 4.1666666666666666666666666666667;
 
-    private const DEFAULT_DRAW_PROBABILITY = 0.10;
+    private const float DEFAULT_DRAW_PROBABILITY = 0.10;
 
     /**
      * Default initial mean / 300
      */
-    private const DEFAULT_DYNAMICS_FACTOR = 0.083333333333333333333333333333333;
+    private const float DEFAULT_DYNAMICS_FACTOR = 0.083333333333333333333333333333333;
 
-    private const DEFAULT_INITIAL_MEAN = 25.0;
+    private const float DEFAULT_INITIAL_MEAN = 25.0;
 
-    private const DEFAULT_INITIAL_STANDARD_DEVIATION = 8.3333333333333333333333333333333;
+    private const float DEFAULT_INITIAL_STANDARD_DEVIATION = 8.3333333333333333333333333333333;
 
     public function __construct(
-        private readonly float $initialMean = self::DEFAULT_INITIAL_MEAN,
-        private readonly float $initialStandardDeviation = self::DEFAULT_INITIAL_STANDARD_DEVIATION,
-        private readonly float $beta = self::DEFAULT_BETA,
-        private readonly float $dynamicsFactor = self::DEFAULT_DYNAMICS_FACTOR,
-        private readonly float $drawProbability = self::DEFAULT_DRAW_PROBABILITY
+        private float $initialMean = self::DEFAULT_INITIAL_MEAN,
+        private float $initialStdDev = self::DEFAULT_INITIAL_STANDARD_DEVIATION,
+        private float $beta = self::DEFAULT_BETA,
+        private float $dynamicsFactor = self::DEFAULT_DYNAMICS_FACTOR,
+        private float $drawProbability = self::DEFAULT_DRAW_PROBABILITY
     )
     {
     }
@@ -42,7 +42,7 @@ class GameInfo
 
     public function getInitialStandardDeviation(): float
     {
-        return $this->initialStandardDeviation;
+        return $this->initialStdDev;
     }
 
     public function getBeta(): float
@@ -62,6 +62,6 @@ class GameInfo
 
     public function getDefaultRating(): Rating
     {
-        return new Rating($this->initialMean, $this->initialStandardDeviation);
+        return new Rating($this->initialMean, $this->initialStdDev);
     }
 }

src/Guard.php

@@ -11,7 +11,7 @@ use Exception;
  *
  * @see http://www.moserware.com/2008/01/borrowing-ideas-from-3-interesting.html
  */
-class Guard
+final class Guard
 {
     public static function argumentIsValidIndex(int $index, int $count, string $parameterName): void
     {
@@ -23,7 +23,7 @@ class Guard
     public static function argumentInRangeInclusive(float $value, float $min, float $max, string $parameterName): void
     {
         if (($value < $min) || ($value > $max)) {
-            throw new Exception($parameterName . ' is not in the valid range [' . $min . ', ' . $max . ']');
+            throw new Exception($parameterName . ' is not in the valid range [' . (int)$min . ', ' . (int)$max . ']');
         }
     }
 }

src/HashMap.php

@@ -7,15 +7,15 @@ namespace DNW\Skills;
 /**
  * Basic hashmap that supports object keys.
  */
-class HashMap
+final class HashMap
 {
     /**
-     * @var mixed[] $hashToValue
+     * @var mixed[] $hashToValue Store the hash to value mapping.
      */
     private array $hashToValue = [];
 
     /**
-     * @var mixed[] $hashToKey
+     * @var mixed[] $hashToKey Store the hash to original key mapping.
      */
     private array $hashToKey = [];
 

src/Numerics/BasicMath.php

@@ -10,24 +10,24 @@ namespace DNW\Skills\Numerics;
  * @author    Jeff Moser <jeff@moserware.com>
  * @copyright 2010 Jeff Moser
  */
-class BasicMath
+final class BasicMath
 {
     /**
-     * Squares the input (x^2 = x * x)
+     * Squares the input (input^2 = input * input)
      *
-     * @param $x Value to square (x)
+     * @param $input Value to square (input)
      *
-     * @return float The squared value (x^2)
+     * @return float The squared value (input^2)
      */
-    public static function square(float $x): float
+    public static function square(float $input): float
     {
-        return $x * $x;
+        return $input * $input;
     }
 
     /**
      * Sums the items in $itemsToSum
      *
-     * @param mixed[]    $itemsToSum The items to sum,
+     * @param mixed[]    $itemsToSum The items to sum.
      * @param \Closure $callback   The function to apply to each array element before summing.
      *
      * @return float The sum.

src/Numerics/GaussianDistribution.php

@@ -10,11 +10,11 @@ namespace DNW\Skills\Numerics;
  * @author    Jeff Moser <jeff@moserware.com>
  * @copyright 2010 Jeff Moser
  */
-class GaussianDistribution
+final class GaussianDistribution
 {
-    private const DEFAULT_STANDARD_DEVIATION = 1.0;
+    private const float DEFAULT_STANDARD_DEVIATION = 1.0;
 
-    private const DEFAULT_MEAN = 0.0;
+    private const float DEFAULT_MEAN = 0.0;
 
     /**
      * Square Root 2π.
@@ -23,7 +23,7 @@ class GaussianDistribution
      *
      * @link https://www.wolframalpha.com/input?i=sqrt%282*pi%29 Source of value
      */
-    private const M_SQRT_2_PI = 2.5066282746310005024157652848110452530069867406099383166299235763;
+    private const float M_SQRT_2_PI = 2.5066282746310005024157652848110452530069867406099383166299235763;
 
     /**
      * Log of Square Root 2π.
@@ -32,10 +32,11 @@ class GaussianDistribution
      *
      * @link https://www.wolframalpha.com/input?i=log%28sqrt%282*pi%29%29 Source of value
      */
-    private const M_LOG_SQRT_2_PI = 0.9189385332046727417803297364056176398613974736377834128171515404;
+    private const float M_LOG_SQRT_2_PI = 0.9189385332046727417803297364056176398613974736377834128171515404;
 
-    // precision and precisionMean are used because they make multiplying and dividing simpler
-    // (see the accompanying math paper for more details)
+    /**
+     * Precision and precisionMean are used because they make multiplying and dividing simpler.
+     */
     private float $precision = 1.0;
 
     private float $precisionMean = 0.0;
@@ -55,7 +56,6 @@ class GaussianDistribution
             $this->precisionMean = $this->precision * $this->mean;
         } else {
             $this->precision = \INF;
-
             $this->precisionMean = $this->mean == 0 ? 0 : \INF;
         }
     }
@@ -172,10 +172,10 @@ class GaussianDistribution
         $meanDifference = $numerator->mean - $denominator->mean;
 
         return log($denominator->variance) + self::M_LOG_SQRT_2_PI - log($varianceDifference) / 2.0 +
-        BasicMath::square($meanDifference) / (2 * $varianceDifference);
+        BasicMath::square($meanDifference) / (2.0 * $varianceDifference);
     }
 
-    public static function at(float $x, float $mean = 0.0, float $standardDeviation = 1.0): float
+    public static function at(float $var, float $mean = 0.0, float $standardDeviation = 1.0): float
     {
         // See http://mathworld.wolfram.com/NormalDistribution.html
         //                1              -(x-mean)^2 / (2*stdDev^2)
@@ -183,25 +183,25 @@ class GaussianDistribution
         //        stdDev * sqrt(2*pi)
 
         $multiplier = 1.0 / ($standardDeviation * self::M_SQRT_2_PI);
-        $expPart = exp((-1.0 * BasicMath::square($x - $mean)) / (2 * BasicMath::square($standardDeviation)));
+        $expPart = exp((-1.0 * BasicMath::square($var - $mean)) / (2.0 * BasicMath::square($standardDeviation)));
 
         return $multiplier * $expPart;
     }
 
-    public static function cumulativeTo(float $x): float
+    public static function cumulativeTo(float $var): float
     {
-        $result = GaussianDistribution::errorFunctionCumulativeTo(-M_SQRT1_2 * $x);
+        $result = GaussianDistribution::errorFunctionCumulativeTo(-M_SQRT1_2 * $var);
 
         return 0.5 * $result;
     }
 
-    private static function errorFunctionCumulativeTo(float $x): float
+    private static function errorFunctionCumulativeTo(float $var): float
     {
         // Derived from page 265 of Numerical Recipes 3rd Edition
-        $z = abs($x);
+        $z = abs($var);
 
         $t = 2.0 / (2.0 + $z);
-        $ty = 4 * $t - 2;
+        $ty = 4.0 * $t - 2.0;
 
         $coefficients = [
             -1.3026537197817094,
@@ -246,7 +246,7 @@ class GaussianDistribution
 
         $ans = $t * exp(-$z * $z + 0.5 * ($coefficients[0] + $ty * $d) - $dd);
 
-        return ($x >= 0.0) ? $ans : (2.0 - $ans);
+        return ($var >= 0.0) ? $ans : (2.0 - $ans);
     }
 
     private static function inverseErrorFunctionCumulativeTo(float $p): float
@@ -260,8 +260,8 @@ class GaussianDistribution
             return 100;
         }
 
-        $pp = ($p < 1.0) ? $p : 2 - $p;
-        $t = sqrt(-2 * log($pp / 2.0)); // Initial guess
+        $pp = ($p < 1.0) ? $p : 2.0 - $p;
+        $t = sqrt(-2.0 * log($pp / 2.0)); // Initial guess
         $x = -M_SQRT1_2 * ((2.30753 + $t * 0.27061) / (1.0 + $t * (0.99229 + $t * 0.04481)) - $t);
 
         for ($j = 0; $j < 2; ++$j) {
@@ -272,9 +272,9 @@ class GaussianDistribution
         return ($p < 1.0) ? $x : -$x;
     }
 
-    public static function inverseCumulativeTo(float $x, float $mean = 0.0, float $standardDeviation = 1.0): float
+    public static function inverseCumulativeTo(float $var, float $mean = 0.0, float $standardDeviation = 1.0): float
     {
         // From numerical recipes, page 320
-        return $mean - M_SQRT2 * $standardDeviation * GaussianDistribution::inverseErrorFunctionCumulativeTo(2 * $x);
+        return $mean - M_SQRT2 * $standardDeviation * GaussianDistribution::inverseErrorFunctionCumulativeTo(2.0 * $var);
     }
 }

src/Numerics/IdentityMatrix.php

@@ -4,7 +4,7 @@ declare(strict_types=1);
 
 namespace DNW\Skills\Numerics;
 
-class IdentityMatrix extends DiagonalMatrix
+final class IdentityMatrix extends DiagonalMatrix
 {
     public function __construct(int $rows)
     {

src/Numerics/Matrix.php

@@ -8,7 +8,7 @@ use Exception;
 
 class Matrix
 {
-    public const ERROR_TOLERANCE = 0.0000000001;
+    public const float ERROR_TOLERANCE = 0.0000000001;
 
     /**
      * @param array<int,array<int,float>> $matrixRowData
@@ -60,13 +60,34 @@ class Matrix
         return $this->columnCount;
     }
 
-    public function getValue(int $row, int $col): float|int
+    private function checkRowCol(int $row, int $col): void
     {
+        if ($row < 0) {
+            throw new Exception("Row negative");
+        }
+
+        if ($row >= $this->getRowCount()) {
+            throw new Exception("Row beyond range");
+        }
+
+        if ($col < 0) {
+            throw new Exception("Column negative");
+        }
+
+        if ($col >= $this->getColumnCount()) {
+            throw new Exception("Column beyond range");
+        }
+    }
+
+    public function getValue(int $row, int $col): float
+    {
+        $this->checkRowCol($row, $col);
         return $this->matrixRowData[$row][$col];
     }
 
     public function setValue(int $row, int $col, float|int $value): void
     {
+        $this->checkRowCol($row, $col);
         $this->matrixRowData[$row][$col] = $value;
     }
 
@@ -76,10 +97,10 @@ class Matrix
         $transposeMatrix = [];
 
         $rowMatrixData = $this->matrixRowData;
-        for ($currentRowTransposeMatrix = 0; $currentRowTransposeMatrix < $this->columnCount; ++$currentRowTransposeMatrix) {
-            for ($currentColumnTransposeMatrix = 0; $currentColumnTransposeMatrix < $this->rowCount; ++$currentColumnTransposeMatrix) {
-                $transposeMatrix[$currentRowTransposeMatrix][$currentColumnTransposeMatrix] =
-                    $rowMatrixData[$currentColumnTransposeMatrix][$currentRowTransposeMatrix];
+        for ($curRowTransposeMx = 0; $curRowTransposeMx < $this->columnCount; ++$curRowTransposeMx) {
+            for ($curColTransposeMx = 0; $curColTransposeMx < $this->rowCount; ++$curColTransposeMx) {
+                $transposeMatrix[$curRowTransposeMx][$curColTransposeMx] =
+                    $rowMatrixData[$curColTransposeMx][$curRowTransposeMx];
             }
         }
 
@@ -100,7 +121,7 @@ class Matrix
 
         if ($this->rowCount == 1) {
             // Really happy path :)
-            return $this->matrixRowData[0][0];
+            return $this->getValue(0, 0);
         }
 
         if ($this->rowCount == 2) {
@@ -109,10 +130,10 @@ class Matrix
             // | a b |
             // | c d |
             // The determinant is ad - bc
-            $a = $this->matrixRowData[0][0];
-            $b = $this->matrixRowData[0][1];
-            $c = $this->matrixRowData[1][0];
-            $d = $this->matrixRowData[1][1];
+            $a = $this->getValue(0, 0);
+            $b = $this->getValue(0, 1);
+            $c = $this->getValue(1, 0);
+            $d = $this->getValue(1, 1);
 
             return $a * $d - $b * $c;
         }
@@ -127,7 +148,7 @@ class Matrix
 
         // I expand along the first row
         for ($currentColumn = 0; $currentColumn < $this->columnCount; ++$currentColumn) {
-            $firstRowColValue = $this->matrixRowData[0][$currentColumn];
+            $firstRowColValue = $this->getValue(0, $currentColumn);
             $cofactor = $this->getCofactor(0, $currentColumn);
             $itemToAdd = $firstRowColValue * $cofactor;
             $result += $itemToAdd;
@@ -152,10 +173,10 @@ class Matrix
             // | d -b |
             // | -c a |
 
-            $a = $this->matrixRowData[0][0];
-            $b = $this->matrixRowData[0][1];
-            $c = $this->matrixRowData[1][0];
-            $d = $this->matrixRowData[1][1];
+            $a = $this->getValue(0, 0);
+            $b = $this->getValue(0, 1);
+            $c = $this->getValue(1, 0);
+            $d = $this->getValue(1, 1);
 
             return new SquareMatrix(
                 $d,
@@ -180,7 +201,7 @@ class Matrix
     public function getInverse(): Matrix|SquareMatrix
     {
         if (($this->rowCount == 1) && ($this->columnCount == 1)) {
-            return new SquareMatrix(1.0 / $this->matrixRowData[0][0]);
+            return new SquareMatrix(1.0 / $this->getValue(0, 0));
         }
 
         // Take the simple approach:
@@ -191,7 +212,7 @@ class Matrix
         return self::scalarMultiply($determinantInverse, $adjugate);
     }
 
-    public static function scalarMultiply(float|int $scalarValue, Matrix $matrix): Matrix
+    public static function scalarMultiply(float $scalarValue, Matrix $matrix): Matrix
     {
         $rows = $matrix->getRowCount();
         $columns = $matrix->getColumnCount();
@@ -244,7 +265,7 @@ class Matrix
 
         for ($currentRow = 0; $currentRow < $resultRows; ++$currentRow) {
             for ($currentColumn = 0; $currentColumn < $resultColumns; ++$currentColumn) {
-                $productValue = 0;
+                $productValue = 0.0;
 
                 for ($vectorIndex = 0; $vectorIndex < $left->getColumnCount(); ++$vectorIndex) {
                     $leftValue = $left->getValue($currentRow, $vectorIndex);
@@ -262,6 +283,7 @@ class Matrix
 
     private function getMinorMatrix(int $rowToRemove, int $columnToRemove): Matrix
     {
+        $this->checkRowCol($rowToRemove, $columnToRemove);
         // See http://en.wikipedia.org/wiki/Minor_(linear_algebra)
 
         // I'm going to use a horribly naïve algorithm... because I can :)
@@ -281,7 +303,7 @@ class Matrix
                     continue;
                 }
 
-                $result[$actualRow][$actualCol] = $this->matrixRowData[$currentRow][$currentColumn];
+                $result[$actualRow][$actualCol] = $this->getValue($currentRow, $currentColumn);
 
                 ++$actualCol;
             }
@@ -294,6 +316,7 @@ class Matrix
 
     public function getCofactor(int $rowToRemove, int $columnToRemove): float
     {
+        $this->checkRowCol($rowToRemove, $columnToRemove);
         // See http://en.wikipedia.org/wiki/Cofactor_(linear_algebra) for details
         // REVIEW: should things be reversed since I'm 0 indexed?
         $sum = $rowToRemove + $columnToRemove;
@@ -316,7 +339,7 @@ class Matrix
             for ($currentColumn = 0; $currentColumn < $this->columnCount; ++$currentColumn) {
                 $delta =
                     abs(
-                        $this->matrixRowData[$currentRow][$currentColumn] -
+                        $this->getValue($currentRow, $currentColumn) -
                         $otherMatrix->getValue($currentRow, $currentColumn)
                     );
 

src/Numerics/SquareMatrix.php

@@ -4,7 +4,7 @@ declare(strict_types=1);
 
 namespace DNW\Skills\Numerics;
 
-class SquareMatrix extends Matrix
+final class SquareMatrix extends Matrix
 {
     public function __construct(float|int ...$allValues)
     {

src/Numerics/Vector.php

@@ -4,7 +4,7 @@ declare(strict_types=1);
 
 namespace DNW\Skills\Numerics;
 
-class Vector extends Matrix
+final class Vector extends Matrix
 {
     /**
      * @param float[] $vectorValues

src/PartialPlay.php

@@ -4,18 +4,18 @@ declare(strict_types=1);
 
 namespace DNW\Skills;
 
-class PartialPlay
+final class PartialPlay
 {
     public static function getPartialPlayPercentage(Player $player): float
     {
-        $partialPlayPercentage = $player->getPartialPlayPercentage();
+        $partialPlayPct = $player->getPartialPlayPercentage();
 
         // HACK to get around bug near 0
-        $smallestPercentage = 0.0001;
-        if ($partialPlayPercentage < $smallestPercentage) {
-            return $smallestPercentage;
+        $smallestPct = 0.0001;
+        if ($partialPlayPct < $smallestPct) {
+            return $smallestPct;
         }
 
-        return $partialPlayPercentage;
+        return $partialPlayPct;
     }
 }

src/Player.php

@@ -7,33 +7,39 @@ namespace DNW\Skills;
 /**
  * Represents a player who has a Rating.
  */
-class Player implements ISupportPartialPlay, ISupportPartialUpdate
+final readonly class Player implements ISupportPartialPlay, ISupportPartialUpdate
 {
-    private const DEFAULT_PARTIAL_PLAY_PERCENTAGE = 1.0; // = 100% play time
+    private const float DEFAULT_PARTIAL_PLAY_PERCENTAGE = 1.0; // = 100% play time
 
-    private const DEFAULT_PARTIAL_UPDATE_PERCENTAGE = 1.0;
+    private const float DEFAULT_PARTIAL_UPDATE_PERCENTAGE = 1.0;
 
-    private readonly float $PartialPlayPercentage;
+    /**
+     * @var float The weight percentage to give this player when calculating a new rank.
+     */
+    private float $PartialPlayPct;
 
-    private readonly float $PartialUpdatePercentage;
+    /**
+     * @var float Indicated how much of a skill update a player should receive where 0 represents no update and 1.0 represents 100% of the update.
+     */
+    private float $PartialUpdatePct;
 
     /**
      * Constructs a player.
      *
-     * @param string|int $Id                      The identifier for the player, such as a name.
-     * @param float $partialPlayPercentage   The weight percentage to give this player when calculating a new rank.
-     * @param float $partialUpdatePercentage Indicated how much of a skill update a player should receive where 0 represents no update and 1.0 represents 100% of the update.
+     * @param string|int $Id          The identifier for the player, such as a name.
+     * @param float $partialPlayPct   The weight percentage to give this player when calculating a new rank.
+     * @param float $partialUpdatePct Indicated how much of a skill update a player should receive where 0 represents no update and 1.0 represents 100% of the update.
      */
     public function __construct(
-        private readonly mixed $Id,
-        float $partialPlayPercentage = self::DEFAULT_PARTIAL_PLAY_PERCENTAGE,
-        float $partialUpdatePercentage = self::DEFAULT_PARTIAL_UPDATE_PERCENTAGE
+        private mixed $Id,
+        float $partialPlayPct = self::DEFAULT_PARTIAL_PLAY_PERCENTAGE,
+        float $partialUpdatePct = self::DEFAULT_PARTIAL_UPDATE_PERCENTAGE
     )
     {
-        Guard::argumentInRangeInclusive($partialPlayPercentage, 0.0, 1.0, 'partialPlayPercentage');
-        Guard::argumentInRangeInclusive($partialUpdatePercentage, 0, 1.0, 'partialUpdatePercentage');
-        $this->PartialPlayPercentage = $partialPlayPercentage;
-        $this->PartialUpdatePercentage = $partialUpdatePercentage;
+        Guard::argumentInRangeInclusive($partialPlayPct, 0.0, 1.0, 'partialPlayPercentage');
+        Guard::argumentInRangeInclusive($partialUpdatePct, 0, 1.0, 'partialUpdatePercentage');
+        $this->PartialPlayPct = $partialPlayPct;
+        $this->PartialUpdatePct = $partialUpdatePct;
     }
 
     /**
@@ -47,16 +53,18 @@ class Player implements ISupportPartialPlay, ISupportPartialUpdate
     /**
      * Indicates the percent of the time the player should be weighted where 0.0 indicates the player didn't play and 1.0 indicates the player played 100% of the time.
      */
+    #[\Override]
     public function getPartialPlayPercentage(): float
     {
-        return $this->PartialPlayPercentage;
+        return $this->PartialPlayPct;
     }
 
     /**
      * Indicated how much of a skill update a player should receive where 0.0 represents no update and 1.0 represents 100% of the update.
      */
+    #[\Override]
     public function getPartialUpdatePercentage(): float
     {
-        return $this->PartialUpdatePercentage;
+        return $this->PartialUpdatePct;
     }
 }

src/PlayersRange.php

@@ -6,6 +6,6 @@ namespace DNW\Skills;
 
 use DNW\Skills\Numerics\Range;
 
-class PlayersRange extends Range
+final class PlayersRange extends Range
 {
 }

src/RankSorter.php

@@ -7,7 +7,7 @@ namespace DNW\Skills;
 /**
  * Helper class to sort ranks in non-decreasing order.
  */
-class RankSorter
+final class RankSorter
 {
     /**
      * Performs an in-place sort of the items in according to the ranks in non-decreasing order.

src/Rating.php

@@ -9,18 +9,18 @@ use DNW\Skills\Numerics\GaussianDistribution;
 /**
  * Container for a player's rating.
  */
-class Rating
+final readonly class Rating
 {
-    private const CONSERVATIVE_STANDARD_DEVIATION_MULTIPLIER = 3;
+    private const float CONSERVATIVE_STANDARD_DEVIATION_MULTIPLIER = 3;
 
     /**
      * Constructs a rating.
      *
      * @param float     $mean                                    The statistical mean value of the rating (also known as mu).
      * @param float     $standardDeviation                       The standard deviation of the rating (also known as s).
-     * @param float|int $conservativeStandardDeviationMultiplier optional The number of standardDeviations to subtract from the mean to achieve a conservative rating.
+     * @param float     $conservativeStandardDeviationMultiplier optional The number of standardDeviations to subtract from the mean to achieve a conservative rating.
      */
-    public function __construct(private readonly float $mean, private readonly float $standardDeviation, private readonly float|int $conservativeStandardDeviationMultiplier = self::CONSERVATIVE_STANDARD_DEVIATION_MULTIPLIER)
+    public function __construct(private float $mean, private float $standardDeviation, private float $conservativeStandardDeviationMultiplier = self::CONSERVATIVE_STANDARD_DEVIATION_MULTIPLIER)
     {
     }
 

src/RatingContainer.php

@@ -6,6 +6,9 @@ namespace DNW\Skills;
 
 class RatingContainer
 {
+    /**
+     * Link Player to a Rating using a hash map.
+     */
     private readonly HashMap $playerToRating;
 
     public function __construct()

src/SkillCalculator.php

@@ -11,6 +11,12 @@ use Exception;
  */
 abstract class SkillCalculator
 {
+    public const int NONE = 0x00;
+
+    public const int PARTIAL_PLAY = 0x01;
+
+    public const int PARTIAL_UPDATE = 0x02;
+
     protected function __construct(
         private readonly int $supportedOptions,
         private readonly TeamsRange $totalTeamsAllowed,
@@ -46,7 +52,7 @@ abstract class SkillCalculator
 
     public function isSupported(int $option): bool
     {
-        return (bool)($this->supportedOptions & $option) == $option;
+        return ($this->supportedOptions & $option) === $option;
     }
 
     /**
@@ -58,7 +64,7 @@ abstract class SkillCalculator
     }
 
     /**
-     * @param array<\DNW\Skills\Team> $teams
+     * @param Team[] $teams
      *
      * @throws \Exception
      */

src/SkillCalculatorSupportedOptions.php

@@ -1,14 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace DNW\Skills;
-
-class SkillCalculatorSupportedOptions
-{
-    public const NONE = 0x00;
-
-    public const PARTIAL_PLAY = 0x01;
-
-    public const PARTIAL_UPDATE = 0x02;
-}

src/Team.php

@@ -4,9 +4,9 @@ declare(strict_types=1);
 
 namespace DNW\Skills;
 
-class Team extends RatingContainer
+final class Team extends RatingContainer
 {
-    public function __construct(Player $player = NULL, Rating $rating = NULL)
+    public function __construct(?Player $player = NULL, ?Rating $rating = NULL)
     {
         parent::__construct();
         if (! $player instanceof Player) {

src/TeamsRange.php

@@ -6,6 +6,6 @@ namespace DNW\Skills;
 
 use DNW\Skills\Numerics\Range;
 
-class TeamsRange extends Range
+final class TeamsRange extends Range
 {
 }

src/TrueSkill/DrawMargin.php

@@ -18,6 +18,6 @@ final class DrawMargin
         //
         // margin = inversecdf((draw probability + 1)/2) * sqrt(n1+n2) * beta
         // n1 and n2 are the number of players on each team
-        return GaussianDistribution::inverseCumulativeTo(.5 * ($drawProbability + 1), 0, 1) * M_SQRT2 * $beta;
+        return GaussianDistribution::inverseCumulativeTo(0.5 * ($drawProbability + 1.0), 0.0, 1.0) * M_SQRT2 * $beta;
     }
 }

src/TrueSkill/FactorGraphTrueSkillCalculator.php

@@ -14,7 +14,6 @@ use DNW\Skills\PartialPlay;
 use DNW\Skills\PlayersRange;
 use DNW\Skills\RankSorter;
 use DNW\Skills\SkillCalculator;
-use DNW\Skills\SkillCalculatorSupportedOptions;
 use DNW\Skills\Team;
 use DNW\Skills\TeamsRange;
 use DNW\Skills\RatingContainer;
@@ -23,16 +22,17 @@ use DNW\Skills\Rating;
 /**
  * Calculates TrueSkill using a full factor graph.
  */
-class FactorGraphTrueSkillCalculator extends SkillCalculator
+final class FactorGraphTrueSkillCalculator extends SkillCalculator
 {
     public function __construct()
     {
-        parent::__construct(SkillCalculatorSupportedOptions::PARTIAL_PLAY | SkillCalculatorSupportedOptions::PARTIAL_UPDATE, TeamsRange::atLeast(2), PlayersRange::atLeast(1));
+        parent::__construct(SkillCalculator::PARTIAL_PLAY | SkillCalculator::PARTIAL_UPDATE, TeamsRange::atLeast(2), PlayersRange::atLeast(1));
     }
 
     /**
      * {@inheritdoc}
      */
+    #[\Override]
     public function calculateNewRatings(
         GameInfo $gameInfo,
         array $teams,
@@ -55,6 +55,7 @@ class FactorGraphTrueSkillCalculator extends SkillCalculator
     /**
      * {@inheritdoc}
      */
+    #[\Override]
     public function calculateMatchQuality(GameInfo $gameInfo, array $teams): float
     {
         // We need to create the A matrix which is the player team assigments.
@@ -172,7 +173,8 @@ class FactorGraphTrueSkillCalculator extends SkillCalculator
 
         $currentColumn = 0;
 
-        for ($i = 0; $i < count($teamAssignmentsList) - 1; ++$i) {
+        $teamCnt = count($teamAssignmentsList);
+        for ($i = 0; $i < $teamCnt - 1; ++$i) {
             $currentTeam = $teamAssignmentsList[$i];
 
             // Need to add in 0's for all the previous players, since they're not
@@ -190,7 +192,7 @@ class FactorGraphTrueSkillCalculator extends SkillCalculator
             $nextTeam = $teamAssignmentsList[$i + 1];
             foreach ($nextTeam->getAllPlayers() as $nextTeamPlayer) {
                 // Add a -1 * playing time to represent the difference
-                $playerAssignments[$currentColumn][] = -1 * PartialPlay::getPartialPlayPercentage($nextTeamPlayer);
+                $playerAssignments[$currentColumn][] = -1.0 * PartialPlay::getPartialPlayPercentage($nextTeamPlayer);
                 --$rowsRemaining;
             }
 

src/TrueSkill/Factors/GaussianFactor.php

@@ -14,6 +14,7 @@ abstract class GaussianFactor extends Factor
     /**
      * Sends the factor-graph message with and returns the log-normalization constant.
      */
+    #[\Override]
     protected function sendMessageVariable(Message $message, Variable $variable): float|int
     {
         $marginal = $variable->getValue();
@@ -24,6 +25,7 @@ abstract class GaussianFactor extends Factor
         return $logZ;
     }
 
+    #[\Override]
     public function createVariableToMessageBinding(Variable $variable): Message
     {
         $newDistribution = GaussianDistribution::fromPrecisionMean(0, 0);

src/TrueSkill/Factors/GaussianGreaterThanFactor.php

@@ -14,7 +14,7 @@ use DNW\Skills\TrueSkill\TruncatedGaussianCorrectionFunctions;
  *
  * See the accompanying math paper for more details.
  */
-class GaussianGreaterThanFactor extends GaussianFactor
+final class GaussianGreaterThanFactor extends GaussianFactor
 {
     public function __construct(private readonly float $epsilon, Variable $variable)
     {
@@ -22,6 +22,7 @@ class GaussianGreaterThanFactor extends GaussianFactor
         $this->createVariableToMessageBinding($variable);
     }
 
+    #[\Override]
     public function getLogNormalization(): float
     {
         $vars = $this->getVariables();
@@ -42,6 +43,7 @@ class GaussianGreaterThanFactor extends GaussianFactor
         );
     }
 
+    #[\Override]
     protected function updateMessageVariable(Message $message, Variable $variable): float
     {
         $oldMarginal = clone $variable->getValue();

src/TrueSkill/Factors/GaussianLikelihoodFactor.php

@@ -15,7 +15,7 @@ use Exception;
  *
  * See the accompanying math paper for more details.
  */
-class GaussianLikelihoodFactor extends GaussianFactor
+final class GaussianLikelihoodFactor extends GaussianFactor
 {
     private readonly float $precision;
 
@@ -28,10 +28,11 @@ class GaussianLikelihoodFactor extends GaussianFactor
         $this->createVariableToMessageBinding($variable2);
     }
 
+    #[\Override]
     public function getLogNormalization(): float
     {
         /**
- * @var KeyedVariable[]|mixed $vars
+ * @var KeyedVariable[] $vars
 */
         $vars = $this->getVariables();
         /**
@@ -60,9 +61,9 @@ class GaussianLikelihoodFactor extends GaussianFactor
             $a * ($marginal2->getPrecision() - $message2Value->getPrecision())
         );
 
-        $oldMarginalWithoutMessage = GaussianDistribution::divide($marginal1, $message1Value);
+        $oldMarginalWithoutMsg = GaussianDistribution::divide($marginal1, $message1Value);
 
-        $newMarginal = GaussianDistribution::multiply($oldMarginalWithoutMessage, $newMessage);
+        $newMarginal = GaussianDistribution::multiply($oldMarginalWithoutMsg, $newMessage);
 
         // Update the message and marginal
 
@@ -73,6 +74,7 @@ class GaussianLikelihoodFactor extends GaussianFactor
         return GaussianDistribution::subtract($newMarginal, $marginal1);
     }
 
+    #[\Override]
     public function updateMessageIndex(int $messageIndex): float
     {
         $messages = $this->getMessages();

src/TrueSkill/Factors/GaussianPriorFactor.php

@@ -13,7 +13,7 @@ use DNW\Skills\Numerics\GaussianDistribution;
  *
  * See the accompanying math paper for more details.
  */
-class GaussianPriorFactor extends GaussianFactor
+final class GaussianPriorFactor extends GaussianFactor
 {
     private readonly GaussianDistribution $newMessage;
 
@@ -29,6 +29,7 @@ class GaussianPriorFactor extends GaussianFactor
         $this->createVariableToMessageBindingWithMessage($variable, $newMessage);
     }
 
+    #[\Override]
     protected function updateMessageVariable(Message $message, Variable $variable): float
     {
         $oldMarginal = clone $variable->getValue();

src/TrueSkill/Factors/GaussianWeightedSumFactor.php

@@ -16,12 +16,12 @@ use DNW\Skills\Numerics\GaussianDistribution;
  *
  * See the accompanying math paper for more details.
  */
-class GaussianWeightedSumFactor extends GaussianFactor
+final class GaussianWeightedSumFactor extends GaussianFactor
 {
     /**
-     * @var array<int[]> $variableIndexOrdersForWeights
+     * @var array<int[]> $varIndexOrdersForWeights
      */
-    private array $variableIndexOrdersForWeights = [];
+    private array $varIndexOrdersForWeights = [];
 
     /**
      * This following is used for convenience, for example, the first entry is [0, 1, 2]
@@ -58,9 +58,9 @@ class GaussianWeightedSumFactor extends GaussianFactor
         $variablesToSumLength = count($variablesToSum);
 
         // 0..n-1
-        $this->variableIndexOrdersForWeights[0] = [];
+        $this->varIndexOrdersForWeights[0] = [];
         for ($i = 0; $i < ($variablesToSumLength + 1); ++$i) {
-            $this->variableIndexOrdersForWeights[0][] = $i;
+            $this->varIndexOrdersForWeights[0][] = $i;
         }
 
         $variableWeightsLength = count($variableWeights);
@@ -72,12 +72,12 @@ class GaussianWeightedSumFactor extends GaussianFactor
 
         $weightsLength = $variableWeightsLength + 1;
         for ($weightsIndex = 1; $weightsIndex < $weightsLength; ++$weightsIndex) {
-            $currentWeights = \array_fill(0, $variableWeightsLength, 0);
+            $currentWeights = \array_fill(0, $variableWeightsLength, 0.0);
 
-            $variableIndices = \array_fill(0, $variableWeightsLength + 1, 0);
+            $variableIndices = \array_fill(0, $variableWeightsLength + 1, 0.0);
             $variableIndices[0] = $weightsIndex;
 
-            $currentWeightsSquared = \array_fill(0, $variableWeightsLength, 0);
+            $currentWeightsSquared = \array_fill(0, $variableWeightsLength, 0.0);
 
             // keep a single variable to keep track of where we are in the array.
             // This is helpful since we skip over one of the spots
@@ -90,9 +90,9 @@ class GaussianWeightedSumFactor extends GaussianFactor
 
                 $currentWeight = (-$variableWeights[$currentWeightSourceIndex] / $variableWeights[$weightsIndex - 1]);
 
-                if ($variableWeights[$weightsIndex - 1] == 0) {
+                if ($variableWeights[$weightsIndex - 1] == 0.0) {
                     // HACK: Getting around division by zero
-                    $currentWeight = 0;
+                    $currentWeight = 0.0;
                 }
 
                 $currentWeights[$currentDestinationWeightIndex] = $currentWeight;
@@ -112,8 +112,8 @@ class GaussianWeightedSumFactor extends GaussianFactor
 
             $currentWeights[$currentDestinationWeightIndex] = $finalWeight;
             $currentWeightsSquared[$currentDestinationWeightIndex] = BasicMath::square($finalWeight);
-            $variableIndices[count($variableWeights)] = 0;
-            $this->variableIndexOrdersForWeights[] = $variableIndices;
+            $variableIndices[count($variableWeights)] = 0.0;
+            $this->varIndexOrdersForWeights[] = $variableIndices;
 
             $this->weights[$weightsIndex] = $currentWeights;
             $this->weightsSquared[$weightsIndex] = $currentWeightsSquared;
@@ -127,6 +127,7 @@ class GaussianWeightedSumFactor extends GaussianFactor
         }
     }
 
+    #[\Override]
     public function getLogNormalization(): float
     {
         $vars = $this->getVariables();
@@ -160,9 +161,7 @@ class GaussianWeightedSumFactor extends GaussianFactor
 
         // The math works out so that 1/newPrecision = sum of a_i^2 /marginalsWithoutMessages[i]
         $inverseOfNewPrecisionSum = 0.0;
-        $anotherInverseOfNewPrecisionSum = 0.0;
         $weightedMeanSum = 0.0;
-        $anotherWeightedMeanSum = 0.0;
 
         $weightsSquaredLength = count($weightsSquared);
 
@@ -172,16 +171,11 @@ class GaussianWeightedSumFactor extends GaussianFactor
             $inverseOfNewPrecisionSum += $weightsSquared[$i] /
                 ($variables[$i + 1]->getValue()->getPrecision() - $messages[$i + 1]->getValue()->getPrecision());
 
-            $diff = GaussianDistribution::divide($variables[$i + 1]->getValue(), $messages[$i + 1]->getValue());
-            $anotherInverseOfNewPrecisionSum += $weightsSquared[$i] / $diff->getPrecision();
-
             $weightedMeanSum += $weights[$i]
                 *
                 ($variables[$i + 1]->getValue()->getPrecisionMean() - $messages[$i + 1]->getValue()->getPrecisionMean())
                 /
                 ($variables[$i + 1]->getValue()->getPrecision() - $messages[$i + 1]->getValue()->getPrecision());
-
-            $anotherWeightedMeanSum += $weights[$i] * $diff->getPrecisionMean() / $diff->getPrecision();
         }
 
         $newPrecision = 1.0 / $inverseOfNewPrecisionSum;
@@ -204,6 +198,7 @@ class GaussianWeightedSumFactor extends GaussianFactor
         return $finalDiff;
     }
 
+    #[\Override]
     public function updateMessageIndex(int $messageIndex): float
     {
         $allMessages = $this->getMessages();
@@ -214,7 +209,7 @@ class GaussianWeightedSumFactor extends GaussianFactor
         $updatedMessages = [];
         $updatedVariables = [];
 
-        $indicesToUse = $this->variableIndexOrdersForWeights[$messageIndex];
+        $indicesToUse = $this->varIndexOrdersForWeights[$messageIndex];
         // The tricky part here is that we have to put the messages and variables in the same
         // order as the weights. Thankfully, the weights and messages share the same index numbers,
         // so we just need to make sure they're consistent

src/TrueSkill/Factors/GaussianWithinFactor.php

@@ -14,7 +14,7 @@ use DNW\Skills\TrueSkill\TruncatedGaussianCorrectionFunctions;
  *
  * See the accompanying math paper for more details.
  */
-class GaussianWithinFactor extends GaussianFactor
+final class GaussianWithinFactor extends GaussianFactor
 {
     public function __construct(private readonly float $epsilon, Variable $variable)
     {
@@ -23,6 +23,7 @@ class GaussianWithinFactor extends GaussianFactor
         $this->createVariableToMessageBinding($variable);
     }
 
+    #[\Override]
     public function getLogNormalization(): float
     {
         /**
@@ -46,6 +47,7 @@ class GaussianWithinFactor extends GaussianFactor
         return -GaussianDistribution::logProductNormalization($messageFromVariable, $message) + log($z);
     }
 
+    #[\Override]
     protected function updateMessageVariable(Message $message, Variable $variable): float
     {
         $oldMarginal = clone $variable->getValue();

src/TrueSkill/Layers/IteratedTeamDifferencesInnerLayer.php

@@ -11,37 +11,40 @@ use DNW\Skills\TrueSkill\TrueSkillFactorGraph;
 use Exception;
 
 // The whole purpose of this is to do a loop on the bottom
-class IteratedTeamDifferencesInnerLayer extends TrueSkillFactorGraphLayer
+final class IteratedTeamDifferencesInnerLayer extends TrueSkillFactorGraphLayer
 {
     public function __construct(
         TrueSkillFactorGraph $parentGraph,
-        private readonly TeamPerformancesToTeamPerformanceDifferencesLayer $TeamPerformancesToTeamPerformanceDifferencesLayer,
-        private readonly TeamDifferencesComparisonLayer $TeamDifferencesComparisonLayer
+        private readonly TeamPerformancesToTeamPerformanceDifferencesLayer $teamPerformancesToTeamPerformanceDifferencesLayer,
+        private readonly TeamDifferencesComparisonLayer $teamDifferencesComparisonLayer
     )
     {
         parent::__construct($parentGraph);
     }
 
+    #[\Override]
     public function getLocalFactors(): array
     {
         return array_merge(
-            $this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors(),
-            $this->TeamDifferencesComparisonLayer->getLocalFactors()
+            $this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors(),
+            $this->teamDifferencesComparisonLayer->getLocalFactors()
         );
     }
 
+    #[\Override]
     public function buildLayer(): void
     {
         $inputVariablesGroups = $this->getInputVariablesGroups();
-        $this->TeamPerformancesToTeamPerformanceDifferencesLayer->setInputVariablesGroups($inputVariablesGroups);
-        $this->TeamPerformancesToTeamPerformanceDifferencesLayer->buildLayer();
+        $this->teamPerformancesToTeamPerformanceDifferencesLayer->setInputVariablesGroups($inputVariablesGroups);
+        $this->teamPerformancesToTeamPerformanceDifferencesLayer->buildLayer();
 
-        $teamDifferencesOutputVariablesGroups = $this->TeamPerformancesToTeamPerformanceDifferencesLayer->getOutputVariablesGroups();
-        $this->TeamDifferencesComparisonLayer->setInputVariablesGroups($teamDifferencesOutputVariablesGroups);
-        $this->TeamDifferencesComparisonLayer->buildLayer();
+        $teamDifferencesOutputVariablesGroups = $this->teamPerformancesToTeamPerformanceDifferencesLayer->getOutputVariablesGroups();
+        $this->teamDifferencesComparisonLayer->setInputVariablesGroups($teamDifferencesOutputVariablesGroups);
+        $this->teamDifferencesComparisonLayer->buildLayer();
     }
 
-    public function createPriorSchedule(): ?ScheduleSequence
+    #[\Override]
+    public function createPriorSchedule(): ScheduleSequence
     {
         switch (count($this->getInputVariablesGroups())) {
             case 0:
@@ -56,9 +59,9 @@ class IteratedTeamDifferencesInnerLayer extends TrueSkillFactorGraphLayer
         }
 
         // When dealing with differences, there are always (n-1) differences, so add in the 1
-        $totalTeamDifferences = count($this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors());
+        $totalTeamDifferences = count($this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors());
 
-        $localFactors = $this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
+        $localFactors = $this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
 
         $firstDifferencesFactor = $localFactors[0];
         $lastDifferencesFactor = $localFactors[$totalTeamDifferences - 1];
@@ -83,8 +86,8 @@ class IteratedTeamDifferencesInnerLayer extends TrueSkillFactorGraphLayer
 
     private function createTwoTeamInnerPriorLoopSchedule(): ScheduleSequence
     {
-        $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors = $this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
-        $teamDifferencesComparisonLayerLocalFactors = $this->TeamDifferencesComparisonLayer->getLocalFactors();
+        $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors = $this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
+        $teamDifferencesComparisonLayerLocalFactors = $this->teamDifferencesComparisonLayer->getLocalFactors();
 
         $firstPerfToTeamDiff = $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors[0];
         $firstTeamDiffComparison = $teamDifferencesComparisonLayerLocalFactors[0];
@@ -109,13 +112,13 @@ class IteratedTeamDifferencesInnerLayer extends TrueSkillFactorGraphLayer
 
     private function createMultipleTeamInnerPriorLoopSchedule(): ScheduleLoop
     {
-        $totalTeamDifferences = count($this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors());
+        $totalTeamDifferences = count($this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors());
 
         $forwardScheduleList = [];
 
         for ($i = 0; $i < $totalTeamDifferences - 1; ++$i) {
-            $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors = $this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
-            $teamDifferencesComparisonLayerLocalFactors = $this->TeamDifferencesComparisonLayer->getLocalFactors();
+            $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors = $this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
+            $teamDifferencesComparisonLayerLocalFactors = $this->teamDifferencesComparisonLayer->getLocalFactors();
 
             $currentTeamPerfToTeamPerfDiff = $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors[$i];
             $currentTeamDiffComparison = $teamDifferencesComparisonLayerLocalFactors[$i];
@@ -151,8 +154,8 @@ class IteratedTeamDifferencesInnerLayer extends TrueSkillFactorGraphLayer
         $backwardScheduleList = [];
 
         for ($i = 0; $i < $totalTeamDifferences - 1; ++$i) {
-            $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors = $this->TeamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
-            $teamDifferencesComparisonLayerLocalFactors = $this->TeamDifferencesComparisonLayer->getLocalFactors();
+            $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors = $this->teamPerformancesToTeamPerformanceDifferencesLayer->getLocalFactors();
+            $teamDifferencesComparisonLayerLocalFactors = $this->teamDifferencesComparisonLayer->getLocalFactors();
 
             $differencesFactor = $teamPerformancesToTeamPerformanceDifferencesLayerLocalFactors[$totalTeamDifferences - 1 - $i];
             $comparisonFactor = $teamDifferencesComparisonLayerLocalFactors[$totalTeamDifferences - 1 - $i];

src/TrueSkill/Layers/PlayerPerformancesToTeamPerformancesLayer.php

@@ -11,8 +11,9 @@ use DNW\Skills\TrueSkill\Factors\GaussianWeightedSumFactor;
 use DNW\Skills\FactorGraphs\Variable;
 use DNW\Skills\FactorGraphs\KeyedVariable;
 
-class PlayerPerformancesToTeamPerformancesLayer extends TrueSkillFactorGraphLayer
+final class PlayerPerformancesToTeamPerformancesLayer extends TrueSkillFactorGraphLayer
 {
+    #[\Override]
     public function buildLayer(): void
     {
         $inputVariablesGroups = $this->getInputVariablesGroups();
@@ -27,12 +28,13 @@ class PlayerPerformancesToTeamPerformancesLayer extends TrueSkillFactorGraphLaye
             $this->addLayerFactor($newSumFactor);
 
             // REVIEW: Does it make sense to have groups of one?
-            $outputVariablesGroups = &$this->getOutputVariablesGroups();
-            $outputVariablesGroups[] = [$teamPerformance];
+            $outputVarGroups = &$this->getOutputVariablesGroups();
+            $outputVarGroups[] = [$teamPerformance];
         }
     }
 
-    public function createPriorSchedule(): ?ScheduleSequence
+    #[\Override]
+    public function createPriorSchedule(): ScheduleSequence
     {
         $localFactors = $this->getLocalFactors();
 
@@ -49,7 +51,7 @@ class PlayerPerformancesToTeamPerformancesLayer extends TrueSkillFactorGraphLaye
     /**
      * @param KeyedVariable[] $teamMembers
      */
-    protected function createPlayerToTeamSumFactor(array $teamMembers, Variable $sumVariable): GaussianWeightedSumFactor
+    private function createPlayerToTeamSumFactor(array $teamMembers, Variable $sumVariable): GaussianWeightedSumFactor
     {
         $weights = array_map(
             static function ($v): float {
@@ -66,7 +68,8 @@ class PlayerPerformancesToTeamPerformancesLayer extends TrueSkillFactorGraphLaye
         );
     }
 
-    public function createPosteriorSchedule(): ?ScheduleSequence
+    #[\Override]
+    public function createPosteriorSchedule(): ScheduleSequence
     {
         $allFactors = [];
         $localFactors = $this->getLocalFactors();

src/TrueSkill/Layers/PlayerPriorValuesToSkillsLayer.php

@@ -17,7 +17,7 @@ use DNW\Skills\FactorGraphs\ScheduleSequence;
 
 // We intentionally have no Posterior schedule since the only purpose here is to
 // start the process.
-class PlayerPriorValuesToSkillsLayer extends TrueSkillFactorGraphLayer
+final class PlayerPriorValuesToSkillsLayer extends TrueSkillFactorGraphLayer
 {
     /**
      * @param Team[] $teams
@@ -27,6 +27,7 @@ class PlayerPriorValuesToSkillsLayer extends TrueSkillFactorGraphLayer
         parent::__construct($parentGraph);
     }
 
+    #[\Override]
     public function buildLayer(): void
     {
         $teams = $this->teams;
@@ -34,12 +35,12 @@ class PlayerPriorValuesToSkillsLayer extends TrueSkillFactorGraphLayer
             $localCurrentTeam = $currentTeam;
             $currentTeamSkills = [];
 
-            $currentTeamAllPlayers = $localCurrentTeam->getAllPlayers();
-            foreach ($currentTeamAllPlayers as $currentTeamPlayer) {
-                $localCurrentTeamPlayer = $currentTeamPlayer;
-                $currentTeamPlayerRating = $currentTeam->getRating($localCurrentTeamPlayer);
-                $playerSkill = $this->createSkillOutputVariable($localCurrentTeamPlayer);
-                $priorFactor = $this->createPriorFactor($currentTeamPlayerRating, $playerSkill);
+            $curTeamAllPlayers = $localCurrentTeam->getAllPlayers();
+            foreach ($curTeamAllPlayers as $curTeamPlayer) {
+                $localCurTeamPlayer = $curTeamPlayer;
+                $curTeamPlayerRating = $currentTeam->getRating($localCurTeamPlayer);
+                $playerSkill = $this->createSkillOutputVariable($localCurTeamPlayer);
+                $priorFactor = $this->createPriorFactor($curTeamPlayerRating, $playerSkill);
                 $this->addLayerFactor($priorFactor);
                 $currentTeamSkills[] = $playerSkill;
             }
@@ -49,7 +50,8 @@ class PlayerPriorValuesToSkillsLayer extends TrueSkillFactorGraphLayer
         }
     }
 
-    public function createPriorSchedule(): ?ScheduleSequence
+    #[\Override]
+    public function createPriorSchedule(): ScheduleSequence
     {
         $localFactors = $this->getLocalFactors();
 

src/TrueSkill/Layers/PlayerSkillsToPerformancesLayer.php

@@ -11,29 +11,30 @@ use DNW\Skills\Numerics\BasicMath;
 use DNW\Skills\TrueSkill\Factors\GaussianLikelihoodFactor;
 use DNW\Skills\FactorGraphs\ScheduleSequence;
 
-class PlayerSkillsToPerformancesLayer extends TrueSkillFactorGraphLayer
+final class PlayerSkillsToPerformancesLayer extends TrueSkillFactorGraphLayer
 {
+    #[\Override]
     public function buildLayer(): void
     {
-        $inputVariablesGroups = $this->getInputVariablesGroups();
-        $outputVariablesGroups = &$this->getOutputVariablesGroups();
+        $inputVarGroups = $this->getInputVariablesGroups();
+        $outputVarGroups = &$this->getOutputVariablesGroups();
 
-        foreach ($inputVariablesGroups as $currentTeam) {
+        foreach ($inputVarGroups as $currentTeam) {
             $currentTeamPlayerPerformances = [];
 
             /**
-             * @var Variable $playerSkillVariable
+             * @var Variable $playerSkillVar
              */
-            foreach ($currentTeam as $playerSkillVariable) {
-                $localPlayerSkillVariable = $playerSkillVariable;
-                $currentPlayer = ($localPlayerSkillVariable instanceof KeyedVariable) ? $localPlayerSkillVariable->getKey() : "";
+            foreach ($currentTeam as $playerSkillVar) {
+                $localPlayerSkillVar = $playerSkillVar;
+                $currentPlayer = ($localPlayerSkillVar instanceof KeyedVariable) ? $localPlayerSkillVar->getKey() : "";
                 $playerPerformance = $this->createOutputVariable($currentPlayer);
-                $newLikelihoodFactor = $this->createLikelihood($localPlayerSkillVariable, $playerPerformance);
+                $newLikelihoodFactor = $this->createLikelihood($localPlayerSkillVar, $playerPerformance);
                 $this->addLayerFactor($newLikelihoodFactor);
                 $currentTeamPlayerPerformances[] = $playerPerformance;
             }
 
-            $outputVariablesGroups[] = $currentTeamPlayerPerformances;
+            $outputVarGroups[] = $currentTeamPlayerPerformances;
         }
     }
 
@@ -51,7 +52,8 @@ class PlayerSkillsToPerformancesLayer extends TrueSkillFactorGraphLayer
         return $this->getParentFactorGraph()->getVariableFactory()->createKeyedVariable($key);
     }
 
-    public function createPriorSchedule(): ?ScheduleSequence
+    #[\Override]
+    public function createPriorSchedule(): ScheduleSequence
     {
         $localFactors = $this->getLocalFactors();
 
@@ -65,7 +67,8 @@ class PlayerSkillsToPerformancesLayer extends TrueSkillFactorGraphLayer
         );
     }
 
-    public function createPosteriorSchedule(): ?ScheduleSequence
+    #[\Override]
+    public function createPosteriorSchedule(): ScheduleSequence
     {
         $localFactors = $this->getLocalFactors();
 

src/TrueSkill/Layers/TeamDifferencesComparisonLayer.php

@@ -9,7 +9,7 @@ use DNW\Skills\TrueSkill\Factors\GaussianGreaterThanFactor;
 use DNW\Skills\TrueSkill\Factors\GaussianWithinFactor;
 use DNW\Skills\TrueSkill\TrueSkillFactorGraph;
 
-class TeamDifferencesComparisonLayer extends TrueSkillFactorGraphLayer
+final class TeamDifferencesComparisonLayer extends TrueSkillFactorGraphLayer
 {
     private readonly float $epsilon;
 
@@ -23,6 +23,7 @@ class TeamDifferencesComparisonLayer extends TrueSkillFactorGraphLayer
         $this->epsilon = DrawMargin::getDrawMarginFromDrawProbability($gameInfo->getDrawProbability(), $gameInfo->getBeta());
     }
 
+    #[\Override]
     public function buildLayer(): void
     {
         $inputVarGroups = $this->getInputVariablesGroups();

src/TrueSkill/Layers/TeamPerformancesToTeamPerformanceDifferencesLayer.php

@@ -7,8 +7,9 @@ namespace DNW\Skills\TrueSkill\Layers;
 use DNW\Skills\FactorGraphs\Variable;
 use DNW\Skills\TrueSkill\Factors\GaussianWeightedSumFactor;
 
-class TeamPerformancesToTeamPerformanceDifferencesLayer extends TrueSkillFactorGraphLayer
+final class TeamPerformancesToTeamPerformanceDifferencesLayer extends TrueSkillFactorGraphLayer
 {
+    #[\Override]
     public function buildLayer(): void
     {
         $inputVariablesGroups = $this->getInputVariablesGroups();
@@ -28,11 +29,7 @@ class TeamPerformancesToTeamPerformanceDifferencesLayer extends TrueSkillFactorG
         }
     }
 
-    private function createTeamPerformanceToDifferenceFactor(
-        Variable $strongerTeam,
-        Variable $weakerTeam,
-        Variable $output
-    ): GaussianWeightedSumFactor
+    private function createTeamPerformanceToDifferenceFactor(Variable $strongerTeam, Variable $weakerTeam, Variable $output): GaussianWeightedSumFactor
     {
         $teams = [$strongerTeam, $weakerTeam];
         $weights = [1.0, -1.0];

src/TrueSkill/Layers/TrueSkillFactorGraphLayer.php

@@ -9,8 +9,4 @@ use DNW\Skills\TrueSkill\TrueSkillFactorGraph;
 
 abstract class TrueSkillFactorGraphLayer extends FactorGraphLayer
 {
-    public function __construct(TrueSkillFactorGraph $parentGraph)
-    {
-        parent::__construct($parentGraph);
-    }
 }

src/TrueSkill/TrueSkillFactorGraph.php

@@ -23,16 +23,18 @@ use DNW\Skills\TrueSkill\Layers\PlayerSkillsToPerformancesLayer;
 use DNW\Skills\TrueSkill\Layers\TeamDifferencesComparisonLayer;
 use DNW\Skills\TrueSkill\Layers\TeamPerformancesToTeamPerformanceDifferencesLayer;
 
-class TrueSkillFactorGraph extends FactorGraph
+final class TrueSkillFactorGraph extends FactorGraph
 {
     /**
      * @var FactorGraphLayer[] $layers
      */
-    private array $layers;
+    private readonly array $layers;
 
     private readonly PlayerPriorValuesToSkillsLayer $priorLayer;
 
     /**
+     * Constructor
+     *
      * @param GameInfo $gameInfo  Parameters for the game.
      * @param Team[]   $teams     A mapping of team players and their ratings.
      * @param int[]    $teamRanks The ranks of the teams where 1 is first place. For a tie, repeat the number (e.g. 1, 2, 2).
@@ -118,9 +120,9 @@ class TrueSkillFactorGraph extends FactorGraph
         $allLayersReverse = array_reverse($this->layers);
 
         foreach ($allLayersReverse as $currentLayer) {
-            $currentPosteriorSchedule = $currentLayer->createPosteriorSchedule();
-            if ($currentPosteriorSchedule != NULL) {
-                $fullSchedule[] = $currentPosteriorSchedule;
+            $curPosteriorSchedule = $currentLayer->createPosteriorSchedule();
+            if ($curPosteriorSchedule != NULL) {
+                $fullSchedule[] = $curPosteriorSchedule;
             }
         }
 

src/TrueSkill/TruncatedGaussianCorrectionFunctions.php

@@ -6,7 +6,7 @@ namespace DNW\Skills\TrueSkill;
 
 use DNW\Skills\Numerics\GaussianDistribution;
 
-class TruncatedGaussianCorrectionFunctions
+final class TruncatedGaussianCorrectionFunctions
 {
     // These functions from the bottom of page 4 of the TrueSkill paper.
 
@@ -102,33 +102,33 @@ class TruncatedGaussianCorrectionFunctions
     }
 
     // the multiplicative correction of a double-sided truncated Gaussian with unit variance
-    public static function wWithinMarginScaled(float $teamPerformanceDifference, float $drawMargin, float $c): float
+    public static function wWithinMarginScaled(float $teamPerformanceDiff, float $drawMargin, float $c): float
     {
-        return self::wWithinMargin($teamPerformanceDifference / $c, $drawMargin / $c);
+        return self::wWithinMargin($teamPerformanceDiff / $c, $drawMargin / $c);
     }
 
     // From F#:
-    public static function wWithinMargin(float $teamPerformanceDifference, float $drawMargin): float
+    public static function wWithinMargin(float $teamPerformanceDiff, float $drawMargin): float
     {
-        $teamPerformanceDifferenceAbsoluteValue = abs($teamPerformanceDifference);
-        $denominator = GaussianDistribution::cumulativeTo($drawMargin - $teamPerformanceDifferenceAbsoluteValue)
+        $teamPerformanceDiffAbsValue = abs($teamPerformanceDiff);
+        $denominator = GaussianDistribution::cumulativeTo($drawMargin - $teamPerformanceDiffAbsValue)
             -
-            GaussianDistribution::cumulativeTo(-$drawMargin - $teamPerformanceDifferenceAbsoluteValue);
+            GaussianDistribution::cumulativeTo(-$drawMargin - $teamPerformanceDiffAbsValue);
 
         if ($denominator < 2.222758749e-162) {
             return 1.0;
         }
 
-        $vt = self::vWithinMargin($teamPerformanceDifferenceAbsoluteValue, $drawMargin);
+        $vt = self::vWithinMargin($teamPerformanceDiffAbsValue, $drawMargin);
 
         return $vt * $vt +
-        (($drawMargin - $teamPerformanceDifferenceAbsoluteValue)
+        (($drawMargin - $teamPerformanceDiffAbsValue)
             *
             GaussianDistribution::at(
-                $drawMargin - $teamPerformanceDifferenceAbsoluteValue
+                $drawMargin - $teamPerformanceDiffAbsValue
             )
-            - (-$drawMargin - $teamPerformanceDifferenceAbsoluteValue)
+            - (-$drawMargin - $teamPerformanceDiffAbsValue)
             *
-            GaussianDistribution::at(-$drawMargin - $teamPerformanceDifferenceAbsoluteValue)) / $denominator;
+            GaussianDistribution::at(-$drawMargin - $teamPerformanceDiffAbsValue)) / $denominator;
     }
 }

src/TrueSkill/TwoPlayerTrueSkillCalculator.php

@@ -13,9 +13,7 @@ use DNW\Skills\RankSorter;
 use DNW\Skills\Rating;
 use DNW\Skills\RatingContainer;
 use DNW\Skills\SkillCalculator;
-use DNW\Skills\SkillCalculatorSupportedOptions;
 use DNW\Skills\TeamsRange;
-use DNW\Skills\Team;
 
 /**
  * Calculates the new ratings for only two players.
@@ -23,21 +21,18 @@ use DNW\Skills\Team;
  * When you only have two players, a lot of the math simplifies. The main purpose of this class
  * is to show the bare minimum of what a TrueSkill implementation should have.
  */
-class TwoPlayerTrueSkillCalculator extends SkillCalculator
+final class TwoPlayerTrueSkillCalculator extends SkillCalculator
 {
     public function __construct()
     {
-        parent::__construct(SkillCalculatorSupportedOptions::NONE, TeamsRange::exactly(2), PlayersRange::exactly(1));
+        parent::__construct(SkillCalculator::NONE, TeamsRange::exactly(2), PlayersRange::exactly(1));
     }
 
     /**
      * {@inheritdoc}
      */
-    public function calculateNewRatings(
-        GameInfo $gameInfo,
-        array $teams,
-        array $teamRanks
-    ): RatingContainer
+    #[\Override]
+    public function calculateNewRatings(GameInfo $gameInfo, array $teams, array $teamRanks): RatingContainer
     {
         // Basic argument checking
         $this->validateTeamCountAndPlayersCountPerTeam($teams);
@@ -96,7 +91,7 @@ class TwoPlayerTrueSkillCalculator extends SkillCalculator
             +
             BasicMath::square($opponentRating->getStandardDeviation())
             +
-            2 * BasicMath::square($gameInfo->getBeta())
+            2.0 * BasicMath::square($gameInfo->getBeta())
         );
 
         $winningMean = $selfRating->getMean();
@@ -119,11 +114,11 @@ class TwoPlayerTrueSkillCalculator extends SkillCalculator
             // non-draw case
             $v = TruncatedGaussianCorrectionFunctions::vExceedsMarginScaled($meanDelta, $drawMargin, $c);
             $w = TruncatedGaussianCorrectionFunctions::wExceedsMarginScaled($meanDelta, $drawMargin, $c);
-            $rankMultiplier = $comparison->value;
+            $rankMultiplier = (float)$comparison->value;
         } else {
             $v = TruncatedGaussianCorrectionFunctions::vWithinMarginScaled($meanDelta, $drawMargin, $c);
             $w = TruncatedGaussianCorrectionFunctions::wWithinMarginScaled($meanDelta, $drawMargin, $c);
-            $rankMultiplier = 1;
+            $rankMultiplier = 1.0;
         }
 
         $meanMultiplier = (BasicMath::square($selfRating->getStandardDeviation()) + BasicMath::square($gameInfo->getDynamicsFactor())) / $c;
@@ -132,7 +127,7 @@ class TwoPlayerTrueSkillCalculator extends SkillCalculator
         $stdDevMultiplier = $varianceWithDynamics / BasicMath::square($c);
 
         $newMean = $selfRating->getMean() + ($rankMultiplier * $meanMultiplier * $v);
-        $newStdDev = sqrt($varianceWithDynamics * (1 - $w * $stdDevMultiplier));
+        $newStdDev = sqrt($varianceWithDynamics * (1.0 - $w * $stdDevMultiplier));
 
         return new Rating($newMean, $newStdDev);
     }
@@ -140,6 +135,7 @@ class TwoPlayerTrueSkillCalculator extends SkillCalculator
     /**
      * {@inheritdoc}
      */
+    #[\Override]
     public function calculateMatchQuality(GameInfo $gameInfo, array $teams): float
     {
         $this->validateTeamCountAndPlayersCountPerTeam($teams);
@@ -160,16 +156,16 @@ class TwoPlayerTrueSkillCalculator extends SkillCalculator
 
         // This is the square root part of the equation:
         $sqrtPart = sqrt(
-            (2 * $betaSquared)
+            (2.0 * $betaSquared)
             /
-            (2 * $betaSquared + $player1SigmaSquared + $player2SigmaSquared)
+            (2.0 * $betaSquared + $player1SigmaSquared + $player2SigmaSquared)
         );
 
         // This is the exponent part of the equation:
         $expPart = exp(
-            (-1 * BasicMath::square($player1Rating->getMean() - $player2Rating->getMean()))
+            (-1.0 * BasicMath::square($player1Rating->getMean() - $player2Rating->getMean()))
             /
-            (2 * (2 * $betaSquared + $player1SigmaSquared + $player2SigmaSquared))
+            (2.0 * (2.0 * $betaSquared + $player1SigmaSquared + $player2SigmaSquared))
         );
 
         return $sqrtPart * $expPart;

src/TrueSkill/TwoTeamTrueSkillCalculator.php

@@ -13,7 +13,6 @@ use DNW\Skills\RankSorter;
 use DNW\Skills\Rating;
 use DNW\Skills\RatingContainer;
 use DNW\Skills\SkillCalculator;
-use DNW\Skills\SkillCalculatorSupportedOptions;
 use DNW\Skills\Team;
 use DNW\Skills\TeamsRange;
 
@@ -22,16 +21,17 @@ use DNW\Skills\TeamsRange;
  *
  * When you only have two teams, the math is still simple: no factor graphs are used yet.
  */
-class TwoTeamTrueSkillCalculator extends SkillCalculator
+final class TwoTeamTrueSkillCalculator extends SkillCalculator
 {
     public function __construct()
     {
-        parent::__construct(SkillCalculatorSupportedOptions::NONE, TeamsRange::exactly(2), PlayersRange::atLeast(1));
+        parent::__construct(SkillCalculator::NONE, TeamsRange::exactly(2), PlayersRange::atLeast(1));
     }
 
     /**
      * {@inheritdoc}
      */
+    #[\Override]
     public function calculateNewRatings(GameInfo $gameInfo, array $teams, array $teamRanks): RatingContainer
     {
         $this->validateTeamCountAndPlayersCountPerTeam($teams);
@@ -64,13 +64,7 @@ class TwoTeamTrueSkillCalculator extends SkillCalculator
         return $results;
     }
 
-    private static function updatePlayerRatings(
-        GameInfo $gameInfo,
-        RatingContainer $newPlayerRatings,
-        Team $selfTeam,
-        Team $otherTeam,
-        PairwiseComparison $selfToOtherTeamComparison
-    ): void
+    private static function updatePlayerRatings(GameInfo $gameInfo, RatingContainer $newPlayerRatings, Team $selfTeam, Team $otherTeam, PairwiseComparison $selfToOtherTeamComparison): void
     {
         $drawMargin = DrawMargin::getDrawMarginFromDrawProbability(
             $gameInfo->getDrawProbability(),
@@ -94,7 +88,7 @@ class TwoTeamTrueSkillCalculator extends SkillCalculator
             +
             BasicMath::sum($otherTeam->getAllRatings(), $varianceGetter)
             +
-            $totalPlayers * $betaSquared
+            (float)$totalPlayers * $betaSquared
         );
 
         $winningMean = $selfMeanSum;
@@ -117,18 +111,18 @@ class TwoTeamTrueSkillCalculator extends SkillCalculator
             // non-draw case
             $v = TruncatedGaussianCorrectionFunctions::vExceedsMarginScaled($meanDelta, $drawMargin, $c);
             $w = TruncatedGaussianCorrectionFunctions::wExceedsMarginScaled($meanDelta, $drawMargin, $c);
-            $rankMultiplier = $selfToOtherTeamComparison->value;
+            $rankMultiplier = (float)$selfToOtherTeamComparison->value;
         } else {
             // assume draw
             $v = TruncatedGaussianCorrectionFunctions::vWithinMarginScaled($meanDelta, $drawMargin, $c);
             $w = TruncatedGaussianCorrectionFunctions::wWithinMarginScaled($meanDelta, $drawMargin, $c);
-            $rankMultiplier = 1;
+            $rankMultiplier = 1.0;
         }
 
         $selfTeamAllPlayers = $selfTeam->getAllPlayers();
-        foreach ($selfTeamAllPlayers as $selfTeamCurrentPlayer) {
-            $localSelfTeamCurrentPlayer = $selfTeamCurrentPlayer;
-            $previousPlayerRating = $selfTeam->getRating($localSelfTeamCurrentPlayer);
+        foreach ($selfTeamAllPlayers as $selfTeamCurPlayer) {
+            $localSelfTeamCurPlayer = $selfTeamCurPlayer;
+            $previousPlayerRating = $selfTeam->getRating($localSelfTeamCurPlayer);
 
             $meanMultiplier = (BasicMath::square($previousPlayerRating->getStandardDeviation()) + $tauSquared) / $c;
             $stdDevMultiplier = (BasicMath::square($previousPlayerRating->getStandardDeviation()) + $tauSquared) / BasicMath::square($c);
@@ -137,16 +131,17 @@ class TwoTeamTrueSkillCalculator extends SkillCalculator
             $newMean = $previousPlayerRating->getMean() + $playerMeanDelta;
 
             $newStdDev = sqrt(
-                (BasicMath::square($previousPlayerRating->getStandardDeviation()) + $tauSquared) * (1 - $w * $stdDevMultiplier)
+                (BasicMath::square($previousPlayerRating->getStandardDeviation()) + $tauSquared) * (1.0 - $w * $stdDevMultiplier)
             );
 
-            $newPlayerRatings->setRating($localSelfTeamCurrentPlayer, new Rating($newMean, $newStdDev));
+            $newPlayerRatings->setRating($localSelfTeamCurPlayer, new Rating($newMean, $newStdDev));
         }
     }
 
     /**
      * {@inheritdoc}
      */
+    #[\Override]
     public function calculateMatchQuality(GameInfo $gameInfo, array $teams): float
     {
         $this->validateTeamCountAndPlayersCountPerTeam($teams);
@@ -158,7 +153,7 @@ class TwoTeamTrueSkillCalculator extends SkillCalculator
         $team2Ratings = $teams[1]->getAllRatings();
         $team2Count = count($team2Ratings);
 
-        $totalPlayers = $team1Count + $team2Count;
+        $totalPlayers = (float)($team1Count + $team2Count);
 
         $betaSquared = BasicMath::square($gameInfo->getBeta());
 
@@ -183,9 +178,9 @@ class TwoTeamTrueSkillCalculator extends SkillCalculator
         );
 
         $expPart = exp(
-            (-1 * BasicMath::square($team1MeanSum - $team2MeanSum))
+            (-1.0 * BasicMath::square($team1MeanSum - $team2MeanSum))
             /
-            (2 * ($totalPlayers * $betaSquared + $team1StdDevSquared + $team2StdDevSquared))
+            (2.0 * ($totalPlayers * $betaSquared + $team1StdDevSquared + $team2StdDevSquared))
         );
 
         return $expPart * $sqrtPart;

tests/FactorGraphs/VariableTest.php

@@ -12,7 +12,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 
 #[CoversClass(Variable::class)]
 #[UsesClass(GaussianDistribution::class)]
-class VariableTest extends TestCase
+final class VariableTest extends TestCase
 {
     public function testGetterSetter(): void
     {

tests/GameInfoTest.php

@@ -12,7 +12,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 
 #[CoversClass(GameInfo::class)]
 #[UsesClass(Rating::class)]
-class GameInfoTest extends TestCase
+final class GameInfoTest extends TestCase
 {
     public function testMembers(): void
     {

tests/GuardTest.php

@@ -10,7 +10,7 @@ use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\CoversClass;
 
 #[CoversClass(Guard::class)]
-class GuardTest extends TestCase
+final class GuardTest extends TestCase
 {
     public function testargumentIsValidIndexArgumentAbove(): void
     {
@@ -28,7 +28,9 @@ class GuardTest extends TestCase
 
     public function testargumentIsValidIndexArgumentValid(): void
     {
-        Guard::argumentIsValidIndex(5, 10, "dummy");
+        Guard::argumentIsValidIndex(0, 10, "dummy");
+        Guard::argumentIsValidIndex(1, 10, "dummy");
+        Guard::argumentIsValidIndex(9, 10, "dummy");
         $this->expectNotToPerformAssertions();
     }
 
@@ -48,7 +50,12 @@ class GuardTest extends TestCase
 
     public function testargumentInRangeInclusiveValid(): void
     {
+        Guard::argumentInRangeInclusive(0, 0, 100, "dummy");
+        Guard::argumentInRangeInclusive(1, 0, 100, "dummy");
         Guard::argumentInRangeInclusive(50, 0, 100, "dummy");
+        Guard::argumentInRangeInclusive(99, 0, 100, "dummy");
+        Guard::argumentInRangeInclusive(100, 0, 100, "dummy");
+
         $this->expectNotToPerformAssertions();
     }
 }

tests/HashMapTest.php

@@ -7,9 +7,10 @@ namespace DNW\Skills\Tests;
 use DNW\Skills\HashMap;
 use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\CoversClass;
+use stdClass;
 
 #[CoversClass(HashMap::class)]
-class HashMapTest extends TestCase
+final class HashMapTest extends TestCase
 {
     public function testHashmap(): void
     {
@@ -19,13 +20,14 @@ class HashMapTest extends TestCase
         $this->assertEquals([], $h->getAllValues());
 
 
-        $o1 = new \stdClass();
-        $o2 = new \stdClass();
+        $o1 = new stdClass();
+        $o2 = new stdClass();
 
         $h->setValue($o1, 1);
         $h->setvalue($o2, 2);
 
         $this->assertEquals([1, 2], $h->getAllValues());
+        $this->assertEquals([$o1, $o2], $h->getAllKeys());
 
         $this->assertEquals(1, $h->getvalue($o1));
         $this->assertEquals(2, $h->getvalue($o2));

tests/Numerics/BasicMathTest.php

@@ -9,7 +9,7 @@ use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\CoversClass;
 
 #[CoversClass(BasicMath::class)]
-class BasicMathTest extends TestCase
+final class BasicMathTest extends TestCase
 {
     public function testSquare(): void
     {
@@ -23,7 +23,7 @@ class BasicMathTest extends TestCase
         $arr = [1, 1, 1, 1];
 
         $func_return = static fn(float $f): float => $f;
-        $func_double = static fn(float $f): float => $f * 2;
+        $func_double = static fn(float $f): float => $f * 2.0;
         $this->assertEquals(4, BasicMath::sum($arr, $func_return));
         $this->assertEquals(8, BasicMath::sum($arr, $func_double));
     }

tests/Numerics/GaussianDistributionTest.php

@@ -12,9 +12,9 @@ use PHPUnit\Framework\Attributes\UsesClass;
 
 #[CoversClass(GaussianDistribution::class)]
 #[UsesClass(BasicMath::class)]
-class GaussianDistributionTest extends TestCase
+final class GaussianDistributionTest extends TestCase
 {
-    private const ERROR_TOLERANCE = 0.000001;
+    private const float ERROR_TOLERANCE = 0.000001;
 
     public function testGetters(): void
     {
@@ -24,7 +24,7 @@ class GaussianDistributionTest extends TestCase
         $this->assertEquals(9, $gd->getVariance());
         $this->assertEquals(3, $gd->getStandardDeviation());
         $this->assertEquals(1 / 9, $gd->getPrecision());
-        $this->assertEquals(1 / 9 * 10, $gd->getPrecisionMean());
+        $this->assertEquals(1.0 / 9.0 * 10.0, $gd->getPrecisionMean());
         $this->assertEqualsWithDelta(0.13298076013, $gd->getNormalizationConstant(), GaussianDistributionTest::ERROR_TOLERANCE);
     }
 
@@ -57,7 +57,7 @@ class GaussianDistributionTest extends TestCase
 
         $product2 = GaussianDistribution::multiply($m4s5, $m6s7);
 
-        $expectedMean = (4 * BasicMath::square(7) + 6 * BasicMath::square(5)) / (BasicMath::square(5) + BasicMath::square(7));
+        $expectedMean = (4.0 * BasicMath::square(7) + 6.0 * BasicMath::square(5)) / (BasicMath::square(5) + BasicMath::square(7));
         $this->assertEqualsWithDelta($expectedMean, $product2->getMean(), GaussianDistributionTest::ERROR_TOLERANCE);
 
         $expectedSigma = sqrt(((BasicMath::square(5) * BasicMath::square(7)) / (BasicMath::square(5) + BasicMath::square(7))));
@@ -74,7 +74,7 @@ class GaussianDistributionTest extends TestCase
         $this->assertEqualsWithDelta(2.0, $productDividedByStandardNormal->getMean(), GaussianDistributionTest::ERROR_TOLERANCE);
         $this->assertEqualsWithDelta(3.0, $productDividedByStandardNormal->getStandardDeviation(), GaussianDistributionTest::ERROR_TOLERANCE);
 
-        $product2              = new GaussianDistribution((4 * BasicMath::square(7) + 6 * BasicMath::square(5)) / (BasicMath::square(5) + BasicMath::square(7)), sqrt(((BasicMath::square(5) * BasicMath::square(7)) / (BasicMath::square(5) + BasicMath::square(7)))));
+        $product2              = new GaussianDistribution((4.0 * BasicMath::square(7) + 6.0 * BasicMath::square(5)) / (BasicMath::square(5) + BasicMath::square(7)), sqrt(((BasicMath::square(5) * BasicMath::square(7)) / (BasicMath::square(5) + BasicMath::square(7)))));
         $m4s5                  = new GaussianDistribution(4, 5);
         $product2DividedByM4S5 = GaussianDistribution::divide($product2, $m4s5);
         $this->assertEqualsWithDelta(6.0, $product2DividedByM4S5->getMean(), GaussianDistributionTest::ERROR_TOLERANCE);
@@ -92,6 +92,21 @@ class GaussianDistributionTest extends TestCase
         $m3s4 = new GaussianDistribution(3, 4);
         $lpn2 = GaussianDistribution::logProductNormalization($m1s2, $m3s4);
         $this->assertEqualsWithDelta(-2.5168046699816684, $lpn2, GaussianDistributionTest::ERROR_TOLERANCE);
+
+        $numerator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $denominator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $lrn  = GaussianDistribution::logProductNormalization($numerator, $denominator);
+        $this->assertEquals(0, $lrn);
+
+        $numerator = GaussianDistribution::fromPrecisionMean(1, 1);
+        $denominator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $lrn  = GaussianDistribution::logProductNormalization($numerator, $denominator);
+        $this->assertEquals(0, $lrn);
+
+        $numerator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $denominator = GaussianDistribution::fromPrecisionMean(1, 1);
+        $lrn  = GaussianDistribution::logProductNormalization($numerator, $denominator);
+        $this->assertEquals(0, $lrn);
     }
 
     public function testLogRatioNormalization(): void
@@ -101,6 +116,21 @@ class GaussianDistributionTest extends TestCase
         $m3s4 = new GaussianDistribution(3, 4);
         $lrn  = GaussianDistribution::logRatioNormalization($m1s2, $m3s4);
         $this->assertEqualsWithDelta(2.6157405972171204, $lrn, GaussianDistributionTest::ERROR_TOLERANCE);
+
+        $numerator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $denominator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $lrn  = GaussianDistribution::logRatioNormalization($numerator, $denominator);
+        $this->assertEquals(0, $lrn);
+
+        $numerator = GaussianDistribution::fromPrecisionMean(1, 1);
+        $denominator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $lrn  = GaussianDistribution::logRatioNormalization($numerator, $denominator);
+        $this->assertEquals(0, $lrn);
+
+        $numerator = GaussianDistribution::fromPrecisionMean(1, 0);
+        $denominator = GaussianDistribution::fromPrecisionMean(1, 1);
+        $lrn  = GaussianDistribution::logRatioNormalization($numerator, $denominator);
+        $this->assertEquals(0, $lrn);
     }
 
     public function testAbsoluteDifference(): void
@@ -115,4 +145,27 @@ class GaussianDistributionTest extends TestCase
         $absDiff2 = GaussianDistribution::absoluteDifference($m1s2, $m3s4);
         $this->assertEqualsWithDelta(0.4330127018922193, $absDiff2, GaussianDistributionTest::ERROR_TOLERANCE);
     }
+
+    public function testSubtract(): void
+    {
+        // Verified with Ralf Herbrich's F# implementation
+        $standardNormal = new GaussianDistribution(0, 1);
+        $absDiff        = GaussianDistribution::subtract($standardNormal, $standardNormal);
+        $this->assertEqualsWithDelta(0.0, $absDiff, GaussianDistributionTest::ERROR_TOLERANCE);
+
+        $m1s2 = new GaussianDistribution(1, 2);
+        $m3s4 = new GaussianDistribution(3, 4);
+        $absDiff2 = GaussianDistribution::subtract($m1s2, $m3s4);
+        $this->assertEqualsWithDelta(0.4330127018922193, $absDiff2, GaussianDistributionTest::ERROR_TOLERANCE);
+    }
+
+    public function testfromPrecisionMean(): void
+    {
+        $gd = GaussianDistribution::fromPrecisionMean(0, 0);
+        $this->assertInfinite($gd->getVariance());
+        $this->assertInfinite($gd->getStandardDeviation());
+        $this->assertNan($gd->getMean());
+        $this->assertEquals(0, $gd->getPrecisionMean());
+        $this->assertEquals(0, $gd->getPrecision());
+    }
 }

tests/Numerics/MatrixTest.php

@@ -20,8 +20,85 @@ use Exception;
 #[CoversClass(DiagonalMatrix::class)]
 #[CoversClass(Vector::class)]
 // phpcs:disable PSR2.Methods.FunctionCallSignature,Generic.Functions.FunctionCallArgumentSpacing.TooMuchSpaceAfterComma
-class MatrixTest extends TestCase
+final class MatrixTest extends TestCase
 {
+    public function testEmptyMatrix(): void
+    {
+        $m1 = new Matrix();
+        $this->assertEquals(0, $m1->getRowCount());
+        $this->assertEquals(0, $m1->getColumnCount());
+
+        $m2 = new Matrix(0, 0);
+        $this->assertEquals(0, $m2->getRowCount());
+        $this->assertEquals(0, $m2->getColumnCount());
+
+        $this->assertEquals(new Matrix(), Matrix::multiply($m1, $m2));
+    }
+
+    public function testIndexing(): void
+    {
+        $m = new Matrix(5, 5);
+        $m->setValue(0, 0, 1);
+        $this->assertEquals(1, $m->getValue(0, 0));
+        $m->setValue(0, 1, 2);
+        $this->assertEquals(2, $m->getValue(0, 1));
+        $m->setValue(1, 0, 3);
+        $this->assertEquals(3, $m->getValue(1, 0));
+        $m->setValue(1, 1, 4);
+        $this->assertEquals(4, $m->getValue(1, 1));
+
+        $m->setValue(3, 3, 11);
+        $this->assertEquals(11, $m->getValue(3, 3));
+        $m->setValue(4, 3, 22);
+        $this->assertEquals(22, $m->getValue(4, 3));
+        $m->setValue(3, 4, 33);
+        $this->assertEquals(33, $m->getValue(3, 4));
+        $m->setValue(4, 4, 44);
+        $this->assertEquals(44, $m->getValue(4, 4));
+
+        try {
+            $m->getValue(-1, -1);
+            $this->fail("No exception");
+        } catch (Exception $exception) {
+            $this->assertInstanceOf(Exception::class, $exception);
+        }
+
+        try {
+            $m->getValue(-1, 0);
+            $this->fail("No exception");
+        } catch (Exception $exception) {
+            $this->assertInstanceOf(Exception::class, $exception);
+        }
+
+        try {
+            $m->getValue(0, -1);
+            $this->fail("No exception");
+        } catch (Exception $exception) {
+            $this->assertInstanceOf(Exception::class, $exception);
+        }
+
+        try {
+            $m->getValue(5, 5);
+            $this->fail("No exception");
+        } catch (Exception $exception) {
+            $this->assertInstanceOf(Exception::class, $exception);
+        }
+
+        try {
+            $m->getValue(5, 4);
+            $this->fail("No exception");
+        } catch (Exception $exception) {
+            $this->assertInstanceOf(Exception::class, $exception);
+        }
+
+        try {
+            $m->getValue(4, 5);
+            $this->fail("No exception");
+        } catch (Exception $exception) {
+            $this->assertInstanceOf(Exception::class, $exception);
+        }
+    }
+
     public function testOneByOneDeterminant(): void
     {
         $a = new SquareMatrix(1);
@@ -218,7 +295,7 @@ class MatrixTest extends TestCase
                               1, 0, 6);
 
         $cInverse = $c->getInverse();
-        $d = Matrix::scalarMultiply((1.0 / 22), new SquareMatrix(24, -12, -2,
+        $d = Matrix::scalarMultiply((1.0 / 22.0), new SquareMatrix(24, -12, -2,
                                                                   5,   3, -5,
                                                                  -4, 2, 4));
 

tests/Numerics/RangeTest.php

@@ -10,7 +10,7 @@ use PHPUnit\Framework\Attributes\CoversClass;
 use Exception;
 
 #[CoversClass(Range::class)]
-class RangeTest extends TestCase
+final class RangeTest extends TestCase
 {
     public function testConstructInvalidParam(): void
     {

tests/PartialPlayTest.php

@@ -14,7 +14,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 #[CoversClass(PartialPlay::class)]
 #[UsesClass(Player::class)]
 #[UsesClass(Guard::class)]
-class PartialPlayTest extends TestCase
+final class PartialPlayTest extends TestCase
 {
     public function testgetPartialPlayPercentage(): void
     {

tests/PlayerTest.php

@@ -12,7 +12,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 
 #[CoversClass(Player::class)]
 #[UsesClass(Guard::class)]
-class PlayerTest extends TestCase
+final class PlayerTest extends TestCase
 {
     public function testPlayerObjectGetterSetter(): void
     {

tests/RankSorterTest.php

@@ -9,7 +9,7 @@ use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\CoversClass;
 
 #[CoversClass(RankSorter::class)]
-class RankSorterTest extends TestCase
+final class RankSorterTest extends TestCase
 {
     public function testSort(): void
     {

tests/RatingContainerTest.php

@@ -18,7 +18,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 #[UsesClass(Player::class)]
 #[UsesClass(Rating::class)]
 #[UsesClass(Guard::class)]
-class RatingContainerTest extends TestCase
+final class RatingContainerTest extends TestCase
 {
     public function testRatingContainer(): void
     {

tests/RatingTest.php

@@ -14,7 +14,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 #[CoversClass(Rating::class)]
 #[UsesClass(BasicMath::class)]
 #[UsesClass(GaussianDistribution::class)]
-class RatingTest extends TestCase
+final class RatingTest extends TestCase
 {
     public function testGetRatingParameters(): void
     {

tests/SkillCalculatorTest.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DNW\Skills\Tests;
+
+use DNW\Skills\SkillCalculator;
+use DNW\Skills\TeamsRange;
+use DNW\Skills\PlayersRange;
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\UsesClass;
+use PHPUnit\Framework\Attributes\RequiresPhpunit;
+
+#[CoversClass(SkillCalculator::class)]
+#[UsesClass(\DNW\Skills\Numerics\Range::class)]
+#[UsesClass(PlayersRange::class)]
+#[UsesClass(TeamsRange::class)]
+#[RequiresPhpunit('<12.0')]
+final class SkillCalculatorTest extends TestCase
+{
+    public function testisSupported(): void
+    {
+        $calculator = $this->getMockForAbstractClass(SkillCalculator::class, [SkillCalculator::PARTIAL_PLAY, new TeamsRange(1, 2), new PlayersRange(1, 2)]);
+
+        $this->assertEquals(TRUE, $calculator->isSupported(SkillCalculator::PARTIAL_PLAY));
+        $this->assertEquals(FALSE, $calculator->isSupported(SkillCalculator::PARTIAL_UPDATE));
+    }
+}

tests/TeamTest.php

@@ -20,7 +20,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 #[UsesClass(Player::class)]
 #[UsesClass(Rating::class)]
 #[UsesClass(Guard::class)]
-class TeamTest extends TestCase
+final class TeamTest extends TestCase
 {
     public function testTeam(): void
     {

tests/TrueSkill/DrawMarginTest.php

@@ -14,9 +14,9 @@ use PHPUnit\Framework\Attributes\UsesClass;
 #[CoversClass(DrawMargin::class)]
 #[UsesClass(BasicMath::class)]
 #[UsesClass(GaussianDistribution::class)]
-class DrawMarginTest extends TestCase
+final class DrawMarginTest extends TestCase
 {
-    private const ERROR_TOLERANCE = 0.000001;
+    private const float ERROR_TOLERANCE = 0.000001;
 
     public function testGetDrawMarginFromDrawProbability(): void
     {

tests/TrueSkill/FactorGraphTrueSkillCalculatorTest.php

@@ -4,22 +4,15 @@ declare(strict_types=1);
 
 namespace DNW\Skills\Tests\TrueSkill;
 
+use DNW\Skills\SkillCalculator;
 use DNW\Skills\GameInfo;
 use DNW\Skills\Player;
 use DNW\Skills\Team;
 use DNW\Skills\TrueSkill\FactorGraphTrueSkillCalculator;
-use DNW\Skills\SkillCalculatorSupportedOptions;
 use PHPUnit\Framework\TestCase;
-use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\Attributes\CoversNothing;
-use PHPUnit\Framework\Attributes\UsesClass;
 
-#[CoversClass(FactorGraphTrueSkillCalculator::class)]
-#[UsesClass(\DNW\Skills\Numerics\Range::class)]
-#[UsesClass(\DNW\Skills\PlayersRange::class)]
-#[UsesClass(\DNW\Skills\SkillCalculator::class)]
-#[UsesClass(\DNW\Skills\TeamsRange::class)]
-class FactorGraphTrueSkillCalculatorTest extends TestCase
+final class FactorGraphTrueSkillCalculatorTest extends TestCase
 {
     #[CoversNothing]
     public function testMicrosoftResearchExample(): void
@@ -75,9 +68,10 @@ class FactorGraphTrueSkillCalculatorTest extends TestCase
         TrueSkillCalculatorTests::testPartialPlayScenarios($this, $calculator);
     }
 
+    #[CoversNothing]
     public function testMethodisSupported(): void
     {
         $calculator = new FactorGraphTrueSkillCalculator();
-        $this->assertEquals(TRUE, $calculator->isSupported(SkillCalculatorSupportedOptions::PARTIAL_PLAY));
+        $this->assertEquals(TRUE, $calculator->isSupported(SkillCalculator::PARTIAL_PLAY));
     }
 }

tests/TrueSkill/TrueSkillCalculatorTests.php

@@ -9,14 +9,13 @@ use DNW\Skills\Player;
 use DNW\Skills\Rating;
 use DNW\Skills\SkillCalculator;
 use DNW\Skills\Team;
-use DNW\Skills\Teams;
 use PHPUnit\Framework\TestCase;
 
-class TrueSkillCalculatorTests
+final class TrueSkillCalculatorTests
 {
-    private const ERROR_TOLERANCE_TRUESKILL = 0.085;
+    private const float ERROR_TOLERANCE_TRUESKILL = 0.085;
 
-    private const ERROR_TOLERANCE_MATCH_QUALITY = 0.0005;
+    private const float ERROR_TOLERANCE_MATCH_QUALITY = 0.0005;
 
     // These are the roll-up ones
 
@@ -70,7 +69,6 @@ class TrueSkillCalculatorTests
     // online calculator at http://atom.research.microsoft.com/trueskill/rankcalculator.aspx
     //
     // All match quality expected values came from the online calculator
-
     // In both cases, there may be some discrepancy after the first decimal point. I think this is due to my implementation
     // using slightly higher precision in GaussianDistribution.
 
@@ -813,15 +811,15 @@ class TrueSkillCalculatorTests
 
     private static function sixteenTeamsOfOneNotDrawn(TestCase $testClass, SkillCalculator $calculator): void
     {
-        $player1 = new Player(1);
-        $player2 = new Player(2);
-        $player3 = new Player(3);
-        $player4 = new Player(4);
-        $player5 = new Player(5);
-        $player6 = new Player(6);
-        $player7 = new Player(7);
-        $player8 = new Player(8);
-        $player9 = new Player(9);
+        $player1  = new Player(1);
+        $player2  = new Player(2);
+        $player3  = new Player(3);
+        $player4  = new Player(4);
+        $player5  = new Player(5);
+        $player6  = new Player(6);
+        $player7  = new Player(7);
+        $player8  = new Player(8);
+        $player9  = new Player(9);
         $player10 = new Player(10);
         $player11 = new Player(11);
         $player12 = new Player(12);
@@ -832,15 +830,15 @@ class TrueSkillCalculatorTests
 
         $gameInfo = new GameInfo();
 
-        $team1 = new Team($player1, $gameInfo->getDefaultRating());
-        $team2 = new Team($player2, $gameInfo->getDefaultRating());
-        $team3 = new Team($player3, $gameInfo->getDefaultRating());
-        $team4 = new Team($player4, $gameInfo->getDefaultRating());
-        $team5 = new Team($player5, $gameInfo->getDefaultRating());
-        $team6 = new Team($player6, $gameInfo->getDefaultRating());
-        $team7 = new Team($player7, $gameInfo->getDefaultRating());
-        $team8 = new Team($player8, $gameInfo->getDefaultRating());
-        $team9 = new Team($player9, $gameInfo->getDefaultRating());
+        $team1 =  new Team($player1, $gameInfo->getDefaultRating());
+        $team2 =  new Team($player2, $gameInfo->getDefaultRating());
+        $team3 =  new Team($player3, $gameInfo->getDefaultRating());
+        $team4 =  new Team($player4, $gameInfo->getDefaultRating());
+        $team5 =  new Team($player5, $gameInfo->getDefaultRating());
+        $team6 =  new Team($player6, $gameInfo->getDefaultRating());
+        $team7 =  new Team($player7, $gameInfo->getDefaultRating());
+        $team8 =  new Team($player8, $gameInfo->getDefaultRating());
+        $team9 =  new Team($player9, $gameInfo->getDefaultRating());
         $team10 = new Team($player10, $gameInfo->getDefaultRating());
         $team11 = new Team($player11, $gameInfo->getDefaultRating());
         $team12 = new Team($player12, $gameInfo->getDefaultRating());
@@ -849,24 +847,7 @@ class TrueSkillCalculatorTests
         $team15 = new Team($player15, $gameInfo->getDefaultRating());
         $team16 = new Team($player16, $gameInfo->getDefaultRating());
 
-        $teams = [
-            $team1,
-            $team2,
-            $team3,
-            $team4,
-            $team5,
-            $team6,
-            $team7,
-            $team8,
-            $team9,
-            $team10,
-            $team11,
-            $team12,
-            $team13,
-            $team14,
-            $team15,
-            $team16
-        ];
+        $teams = [$team1, $team2, $team3, $team4, $team5, $team6, $team7, $team8, $team9, $team10, $team11, $team12, $team13, $team14, $team15, $team16];
 
         $newRatings = $calculator->calculateNewRatings(
             $gameInfo,

tests/TrueSkill/TruncatedGaussianCorrectionFunctionsTest.php

@@ -14,7 +14,7 @@ use PHPUnit\Framework\Attributes\UsesClass;
 #[CoversClass(TruncatedGaussianCorrectionFunctions::class)]
 #[UsesClass(BasicMath::class)]
 #[UsesClass(GaussianDistribution::class)]
-class TruncatedGaussianCorrectionFunctionsTest extends TestCase
+final class TruncatedGaussianCorrectionFunctionsTest extends TestCase
 {
     public function testvGreaterThan(): void
     {

tests/TrueSkill/TwoPlayerTrueSkillCalculatorTest.php

@@ -6,11 +6,9 @@ namespace DNW\Skills\Tests\TrueSkill;
 
 use DNW\Skills\TrueSkill\TwoPlayerTrueSkillCalculator;
 use PHPUnit\Framework\TestCase;
-use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\Attributes\CoversNothing;
 
-#[CoversClass(TwoPlayerTrueSkillCalculator::class)]
-class TwoPlayerTrueSkillCalculatorTest extends TestCase
+final class TwoPlayerTrueSkillCalculatorTest extends TestCase
 {
     #[CoversNothing]
     public function testTwoPlayerTrueSkillCalculator(): void

tests/TrueSkill/TwoTeamTrueSkillCalculatorTest.php

@@ -6,11 +6,9 @@ namespace DNW\Skills\Tests\TrueSkill;
 
 use DNW\Skills\TrueSkill\TwoTeamTrueSkillCalculator;
 use PHPUnit\Framework\TestCase;
-use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\Attributes\CoversNothing;
 
-#[CoversClass(TwoTeamTrueSkillCalculator::class)]
-class TwoTeamTrueSkillCalculatorTest extends TestCase
+final class TwoTeamTrueSkillCalculatorTest extends TestCase
 {
     #[CoversNothing]
     public function testTwoTeamTrueSkillCalculator(): void