Returns an accumulator function which incrementally computes a moving sum of products.
W
parameter defines the number of (x,y) pairs over which to compute the moving sum of products.W
(x,y) pairs 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 = incrmsumprod( 3 );
var sum = accumulator();
// returns null
sum = accumulator( 2.0, 3.0 );
// returns 6.0
sum = accumulator( -5.0, 2.0 );
// returns -4.0
sum = accumulator( 3.0, -2.0 );
// returns -10.0
sum = accumulator( 5.0, 3.0 );
// returns -1.0
sum = accumulator();
// returns -1.0
If provided arguments, returns an updated sum of products; otherwise, returns the current sum of products.
Notes
NaN
or a value which, when used in computations, results inNaN
, the accumulated value isNaN
for all future invocations.value
value
sum of products