/**
* Calculates the standard deviation of the specified elements. If the
* given elements is a population then the population standard deviation
* is calculated otherwise the sample standard deviation.
*
* @param array $elements list of element from a sample or population
* distribution.
* @param boolean $population true if the element list is a population
* distribution.
*
* @return the variance of the specified elements.
*/
public static function standardDeviation($elements, $population = FALSE)
{
return Math::stdv($elements, $population);
}