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