Returns an accumulator function which incrementally computes a moving sum.
W
parameter defines the number of values over which to compute the moving sum.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.window size
accumulator function
var accumulator = incrmsum( 3 );
var sum = accumulator();
// returns null
sum = accumulator( 2.0 );
// returns 2.0
sum = accumulator( -5.0 );
// returns -3.0
sum = accumulator( 3.0 );
// returns 0.0
sum = accumulator( 5.0 );
// returns 3.0
sum = accumulator();
// returns 3.0
If provided a value, returns an updated sum; otherwise, returns the current sum.
Notes
NaN
or a value which, when used in computations, results inNaN
, the accumulated value isNaN
for all future invocations.value
sum