Returns the standard deviation of a degenerate distribution.
constant value of distribution
standard deviation
var v = stdev( 0.1 ); // returns 0.0
var v = stdev( 0.5 ); // returns 0.0
var v = stdev( 10.0 ); // returns 0.0
var v = stdev( NaN ); // returns NaN
Returns the standard deviation of a degenerate distribution.