Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Statistical.php
public static function HARMEAN(...$args)
    {
        // Return value
        $returnValue = Functions::NA();

        // Loop through arguments
        $aArgs = Functions::flattenArray($args);
        if (self::MIN($aArgs) < 0) {
            return Functions::NAN();
        }
        $aCount = 0;
        foreach ($aArgs as $arg) {
            // Is it a numeric value?
            if ((is_numeric($arg)) && (!is_string($arg))) {
                if ($arg <= 0) {
                    return Functions::NAN();
                }
                if ($returnValue === null) {
                    $returnValue = (1 / $arg);
                } else {
                    $returnValue += (1 / $arg);
                }
                ++$aCount;
            }
        }

        // Return
        if ($aCount > 0) {
            return 1 / ($returnValue / $aCount);
        }

        return $returnValue;
    }
public static function HARMEAN(...$args)
    {
        // Return value
        $returnValue = Functions::NA();

        // Loop through arguments
        $aArgs = Functions::flattenArray($args);
        if (self::MIN($aArgs) < 0) {
            return Functions::NAN();
        }
        $aCount = 0;
        foreach ($aArgs as $arg) {
            // Is it a numeric value?
            if ((is_numeric($arg)) && (!is_string($arg))) {
                if ($arg <= 0) {
                    return Functions::NAN();
                }
                if ($returnValue === null) {
                    $returnValue = (1 / $arg);
                } else {
                    $returnValue += (1 / $arg);
                }
                ++$aCount;
            }
        }

        // Return
        if ($aCount > 0) {
            return 1 / ($returnValue / $aCount);
        }

        return $returnValue;
    }
HARMEAN.

Returns the harmonic mean of a data set. The harmonic mean is the reciprocal of the
arithmetic mean of reciprocals.

Excel Function:
HARMEAN(value1[,value2[, ...]])

@category Statistical Functions

@param mixed ...$args Data values

@return float