note 31295 added to ref.math

Here is how to calculate standard deviation in PHP where $samples is an array of incrementing numeric keys and the values are your samples: $sample_count = count($samples); for ($current_sample = 0; $sample_count > $current_sample; ++$current_sample) $sample_square[$current_sample] = pow($samples[$current_sample], 2); $standard_deviation = sqrt(array_sum($sample_square) / $sample_count - pow((array_sum($samples) / $sample_count), 2)); -- http://www.php.net/manual/en/ref.math.php http://master.php.net/manage/user-notes.php?action=edit+31295 http://master.php.net/manage/user-notes.php?action=delete+31295 http://master.php.net/manage/user-notes.php?action=reject+31295