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https://github.com/PHPOffice/PhpSpreadsheet.git
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Vincent Gao
270456a20e
It has no remaining callers (kept only for BC) so nothing else exercises it. Values checked against mpmath's gammainc(a, 0, x); the deep-tail case (a=4, x=80) reproduces the convergence bug this PR fixes.
42 lines
1.7 KiB
PHP
42 lines
1.7 KiB
PHP
<?php
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declare(strict_types=1);
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namespace PhpOffice\PhpSpreadsheetTests\Calculation\Statistical\Distributions;
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use PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions\GammaBase;
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use PHPUnit\Framework\TestCase;
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class GammaBaseTest extends TestCase
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{
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// incompleteGamma() has no remaining callers in this codebase (it is kept for
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// BC), so exercise it directly against reference values from mpmath's
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// gammainc(a, 0, x), i.e. the unregularized lower incomplete gamma.
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#[\PHPUnit\Framework\Attributes\DataProvider('providerIncompleteGamma')]
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public function testIncompleteGamma(float $expectedResult, float $a, float $x): void
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{
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$result = GammaBase::incompleteGamma($a, $x);
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self::assertEqualsWithDelta($expectedResult, $result, abs($expectedResult) * 1.0e-9);
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}
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public static function providerIncompleteGamma(): array
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{
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return [
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'x < a+1, series branch' => [0.26424111765711536, 2.0, 1.0],
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'integer a, x < a+1' => [0.63212055882855768, 1.0, 1.0],
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'non-integer a' => [1.6918067329451983, 0.5, 2.0],
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'x >= a+1, continued-fraction branch' => [11549.765435275602, 10.0, 5.0],
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'x tiny, series branch' => [1.2640079074328247e-8, 2.5, 0.001],
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// the argument the convergence fix targeted: x far past a+1
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'deep tail, x >> a' => [6.0, 4.0, 80.0],
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];
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}
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public function testIncompleteGammaNonPositiveInputsReturnZero(): void
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{
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self::assertSame(0.0, GammaBase::incompleteGamma(2.0, 0.0));
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self::assertSame(0.0, GammaBase::incompleteGamma(2.0, -1.0));
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self::assertSame(0.0, GammaBase::incompleteGamma(0.0, 1.0));
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}
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}
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