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lib/PhpSpreadsheet/Calculation/Statistical/Distributions/Gamma.php

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+<?php
+
+namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical\Distributions;
+
+use PhpOffice\PhpSpreadsheet\Calculation\ArrayEnabled;
+use PhpOffice\PhpSpreadsheet\Calculation\Exception;
+use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
+
+class Gamma extends GammaBase
+{
+    use ArrayEnabled;
+
+    /**
+     * GAMMA.
+     *
+     * Return the gamma function value.
+     *
+     * @param mixed $value Float value for which we want the probability
+     *                      Or can be an array of values
+     *
+     * @return array|float|string The result, or a string containing an error
+     *         If an array of numbers is passed as an argument, then the returned result will also be an array
+     *            with the same dimensions
+     */
+    public static function gamma(mixed $value): array|string|float
+    {
+        if (is_array($value)) {
+            return self::evaluateSingleArgumentArray([self::class, __FUNCTION__], $value);
+        }
+
+        try {
+            $value = DistributionValidations::validateFloat($value);
+        } catch (Exception $e) {
+            return $e->getMessage();
+        }
+
+        if ((((int) $value) == ((float) $value)) && $value <= 0.0) {
+            return ExcelError::NAN();
+        }
+
+        return self::gammaValue($value);
+    }
+
+    /**
+     * GAMMADIST.
+     *
+     * Returns the gamma distribution.
+     *
+     * @param mixed $value Float Value at which you want to evaluate the distribution
+     *                      Or can be an array of values
+     * @param mixed $a Parameter to the distribution as a float
+     *                      Or can be an array of values
+     * @param mixed $b Parameter to the distribution as a float
+     *                      Or can be an array of values
+     * @param mixed $cumulative Boolean value indicating if we want the cdf (true) or the pdf (false)
+     *                      Or can be an array of values
+     *
+     * @return array|float|string If an array of numbers is passed as an argument, then the returned result will also be an array
+     *            with the same dimensions
+     */
+    public static function distribution(mixed $value, mixed $a, mixed $b, mixed $cumulative)
+    {
+        if (is_array($value) || is_array($a) || is_array($b) || is_array($cumulative)) {
+            return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $a, $b, $cumulative);
+        }
+
+        try {
+            $value = DistributionValidations::validateFloat($value);
+            $a = DistributionValidations::validateFloat($a);
+            $b = DistributionValidations::validateFloat($b);
+            $cumulative = DistributionValidations::validateBool($cumulative);
+        } catch (Exception $e) {
+            return $e->getMessage();
+        }
+
+        if (($value < 0) || ($a <= 0) || ($b <= 0)) {
+            return ExcelError::NAN();
+        }
+
+        return self::calculateDistribution($value, $a, $b, $cumulative);
+    }
+
+    /**
+     * GAMMAINV.
+     *
+     * Returns the inverse of the Gamma distribution.
+     *
+     * @param mixed $probability Float probability at which you want to evaluate the distribution
+     *                      Or can be an array of values
+     * @param mixed $alpha Parameter to the distribution as a float
+     *                      Or can be an array of values
+     * @param mixed $beta Parameter to the distribution as a float
+     *                      Or can be an array of values
+     *
+     * @return array|float|string If an array of numbers is passed as an argument, then the returned result will also be an array
+     *            with the same dimensions
+     */
+    public static function inverse(mixed $probability, mixed $alpha, mixed $beta)
+    {
+        if (is_array($probability) || is_array($alpha) || is_array($beta)) {
+            return self::evaluateArrayArguments([self::class, __FUNCTION__], $probability, $alpha, $beta);
+        }
+
+        try {
+            $probability = DistributionValidations::validateProbability($probability);
+            $alpha = DistributionValidations::validateFloat($alpha);
+            $beta = DistributionValidations::validateFloat($beta);
+        } catch (Exception $e) {
+            return $e->getMessage();
+        }
+
+        if (($alpha <= 0.0) || ($beta <= 0.0)) {
+            return ExcelError::NAN();
+        }
+
+        return self::calculateInverse($probability, $alpha, $beta);
+    }
+
+    /**
+     * GAMMALN.
+     *
+     * Returns the natural logarithm of the gamma function.
+     *
+     * @param mixed $value Float Value at which you want to evaluate the distribution
+     *                      Or can be an array of values
+     *
+     * @return array|float|string If an array of numbers is passed as an argument, then the returned result will also be an array
+     *            with the same dimensions
+     */
+    public static function ln(mixed $value): array|string|float
+    {
+        if (is_array($value)) {
+            return self::evaluateSingleArgumentArray([self::class, __FUNCTION__], $value);
+        }
+
+        try {
+            $value = DistributionValidations::validateFloat($value);
+        } catch (Exception $e) {
+            return $e->getMessage();
+        }
+
+        if ($value <= 0) {
+            return ExcelError::NAN();
+        }
+
+        return log(self::gammaValue($value));
+    }
+}