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lib/PhpSpreadsheet/Calculation/Statistical/Deviations.php

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+<?php
+
+namespace PhpOffice\PhpSpreadsheet\Calculation\Statistical;
+
+use PhpOffice\PhpSpreadsheet\Calculation\Functions;
+use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
+
+class Deviations
+{
+    /**
+     * DEVSQ.
+     *
+     * Returns the sum of squares of deviations of data points from their sample mean.
+     *
+     * Excel Function:
+     *        DEVSQ(value1[,value2[, ...]])
+     *
+     * @param mixed ...$args Data values
+     */
+    public static function sumSquares(mixed ...$args): string|float
+    {
+        $aArgs = Functions::flattenArrayIndexed($args);
+
+        $aMean = Averages::average($aArgs);
+        if (!is_numeric($aMean)) {
+            return ExcelError::NAN();
+        }
+
+        // Return value
+        $returnValue = 0.0;
+        $aCount = -1;
+        foreach ($aArgs as $k => $arg) {
+            // Is it a numeric value?
+            if (
+                (is_bool($arg))
+                && ((!Functions::isCellValue($k))
+                    || (Functions::getCompatibilityMode() == Functions::COMPATIBILITY_OPENOFFICE))
+            ) {
+                $arg = (int) $arg;
+            }
+            if ((is_numeric($arg)) && (!is_string($arg))) {
+                $returnValue += ($arg - $aMean) ** 2;
+                ++$aCount;
+            }
+        }
+
+        return $aCount === 0 ? ExcelError::VALUE() : $returnValue;
+    }
+
+    /**
+     * KURT.
+     *
+     * Returns the kurtosis of a data set. Kurtosis characterizes the relative peakedness
+     * or flatness of a distribution compared with the normal distribution. Positive
+     * kurtosis indicates a relatively peaked distribution. Negative kurtosis indicates a
+     * relatively flat distribution.
+     *
+     * @param array ...$args Data Series
+     */
+    public static function kurtosis(...$args): string|int|float
+    {
+        $aArgs = Functions::flattenArrayIndexed($args);
+        $mean = Averages::average($aArgs);
+        if (!is_numeric($mean)) {
+            return ExcelError::DIV0();
+        }
+        $stdDev = (float) StandardDeviations::STDEV($aArgs);
+
+        if ($stdDev > 0) {
+            $count = $summer = 0;
+
+            foreach ($aArgs as $k => $arg) {
+                if ((is_bool($arg)) && (!Functions::isMatrixValue($k))) {
+                } else {
+                    // Is it a numeric value?
+                    if ((is_numeric($arg)) && (!is_string($arg))) {
+                        $summer += (($arg - $mean) / $stdDev) ** 4;
+                        ++$count;
+                    }
+                }
+            }
+
+            if ($count > 3) {
+                return $summer * ($count * ($count + 1)
+                        / (($count - 1) * ($count - 2) * ($count - 3))) - (3 * ($count - 1) ** 2
+                        / (($count - 2) * ($count - 3)));
+            }
+        }
+
+        return ExcelError::DIV0();
+    }
+
+    /**
+     * SKEW.
+     *
+     * Returns the skewness of a distribution. Skewness characterizes the degree of asymmetry
+     * of a distribution around its mean. Positive skewness indicates a distribution with an
+     * asymmetric tail extending toward more positive values. Negative skewness indicates a
+     * distribution with an asymmetric tail extending toward more negative values.
+     *
+     * @param array ...$args Data Series
+     *
+     * @return float|int|string The result, or a string containing an error
+     */
+    public static function skew(...$args): string|int|float
+    {
+        $aArgs = Functions::flattenArrayIndexed($args);
+        $mean = Averages::average($aArgs);
+        if (!is_numeric($mean)) {
+            return ExcelError::DIV0();
+        }
+        $stdDev = StandardDeviations::STDEV($aArgs);
+        if ($stdDev === 0.0 || is_string($stdDev)) {
+            return ExcelError::DIV0();
+        }
+
+        $count = $summer = 0;
+        // Loop through arguments
+        foreach ($aArgs as $k => $arg) {
+            if ((is_bool($arg)) && (!Functions::isMatrixValue($k))) {
+            } elseif (!is_numeric($arg)) {
+                return ExcelError::VALUE();
+            } else {
+                // Is it a numeric value?
+                if ((is_numeric($arg)) && (!is_string($arg))) {
+                    $summer += (($arg - $mean) / $stdDev) ** 3;
+                    ++$count;
+                }
+            }
+        }
+
+        if ($count > 2) {
+            return $summer * ($count / (($count - 1) * ($count - 2)));
+        }
+
+        return ExcelError::DIV0();
+    }
+}