/**
* 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 Data Series
* @return float
*/
public static function KURT()
{
$aArgs = PHPExcel_Calculation_Functions::flattenArray(func_get_args());
$mean = PHPExcel_Calculation_Functions::AVERAGE($aArgs);
$stdDev = PHPExcel_Calculation_Functions::STDEV($aArgs);
if ($stdDev > 0) {
$count = $summer = 0;
// Loop through arguments
foreach ($aArgs as $arg) {
// Is it a numeric value?
if (is_numeric($arg) && !is_string($arg)) {
$summer += pow(($arg - $mean) / $stdDev, 4);
++$count;
}
}
// Return
if ($count > 3) {
return $summer * ($count * ($count + 1) / (($count - 1) * ($count - 2) * ($count - 3))) - 3 * pow($count - 1, 2) / (($count - 2) * ($count - 3));
}
}
return self::$_errorCodes['divisionbyzero'];
}