Returns an accumulator function which incrementally computes an unbiased sample variance.
known mean
accumulator function
var accumulator = incrvariance();
var s2 = accumulator();
// returns null
s2 = accumulator( 2.0 );
// returns 0.0
s2 = accumulator( -5.0 );
// returns 24.5
s2 = accumulator();
// returns 24.5
If provided a value, returns an updated unbiased sample variance; otherwise, returns the current unbiased sample variance.
Notes
NaN
or a value which, when used in computations, results inNaN
, the accumulated value isNaN
for all future invocations.value
unbiased sample variance