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lib/PhpSpreadsheet/Calculation/Statistical/Distributions/F.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 F
+{
+    use ArrayEnabled;
+
+    /**
+     * F.DIST.
+     *
+     *    Returns the F probability distribution.
+     *    You can use this function to determine whether two data sets have different degrees of diversity.
+     *    For example, you can examine the test scores of men and women entering high school, and determine
+     *        if the variability in the females is different from that found in the males.
+     *
+     * @param mixed $value Float value for which we want the probability
+     *                      Or can be an array of values
+     * @param mixed $u The numerator degrees of freedom as an integer
+     *                      Or can be an array of values
+     * @param mixed $v The denominator degrees of freedom as an integer
+     *                      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 $u, mixed $v, mixed $cumulative): array|string|float
+    {
+        if (is_array($value) || is_array($u) || is_array($v) || is_array($cumulative)) {
+            return self::evaluateArrayArguments([self::class, __FUNCTION__], $value, $u, $v, $cumulative);
+        }
+
+        try {
+            $value = DistributionValidations::validateFloat($value);
+            $u = DistributionValidations::validateInt($u);
+            $v = DistributionValidations::validateInt($v);
+            $cumulative = DistributionValidations::validateBool($cumulative);
+        } catch (Exception $e) {
+            return $e->getMessage();
+        }
+
+        if ($value < 0 || $u < 1 || $v < 1) {
+            return ExcelError::NAN();
+        }
+
+        if ($cumulative) {
+            $adjustedValue = ($u * $value) / ($u * $value + $v);
+
+            return Beta::incompleteBeta($adjustedValue, $u / 2, $v / 2);
+        }
+
+        return (Gamma::gammaValue(($v + $u) / 2)
+                / (Gamma::gammaValue($u / 2) * Gamma::gammaValue($v / 2)))
+            * (($u / $v) ** ($u / 2))
+            * (($value ** (($u - 2) / 2)) / ((1 + ($u / $v) * $value) ** (($u + $v) / 2)));
+    }
+}