(PECL stats >= 1.0.0)
stats_standard_deviation — Returns the standard deviation
$a
[, bool $sample = false
] )
Returns the standard deviation of the values in a.
aThe 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.