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{{alias}}( W[, mean] )
Returns an accumulator function which incrementally computes a moving
unbiased sample variance.
The `W` parameter defines the number of values over which to compute the
moving unbiased sample variance.
If provided a value, the accumulator function returns an updated moving
unbiased sample variance. If not provided a value, the accumulator function
returns the current moving unbiased sample variance.
As `W` values are needed to fill the window buffer, the first `W-1` returned
values are calculated from smaller sample sizes. Until the window is full,
each returned value is calculated from all provided values.
Parameters
----------
W: integer
Window size.
mean: number (optional)
Known mean.
Returns
-------
acc: Function
Accumulator function.
Examples
--------
> var accumulator = {{alias}}( 3 );
> var s2 = accumulator()
null
> s2 = accumulator( 2.0 )
0.0
> s2 = accumulator( -5.0 )
24.5
> s2 = accumulator( 3.0 )
19.0
> s2 = accumulator( 5.0 )
28.0
> s2 = accumulator()
28.0
See Also
--------
|
