stats_standard_deviation

(PECL stats >= 1.0.0)

stats_standard_deviation — Returns the standard deviation

function stats_standard_deviation(array $a, bool $sample = false): float

Returns the standard deviation of the values in a.

a: The array of data to find the standard deviation for. Note that all values of the array will be cast to float.
sample: Indicates if a represents a sample of the population; defaults to false.

Returns the standard deviation on success; false on failure.

Raises an E_WARNING when there are fewer than 2 values in a.