
{{alias}}( W[, mx, my] )
    Returns an accumulator function which incrementally computes a moving
    squared sample Pearson product-moment correlation coefficient.

    The `W` parameter defines the number of values over which to compute the
    moving squared sample correlation coefficient.

    If provided values, the accumulator function returns an updated moving
    squared sample correlation coefficient. If not provided values, the
    accumulator function returns the current moving squared sample correlation
    coefficient.

    As `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.

    Parameters
    ----------
    W: integer
        Window size.

    mx: number (optional)
        Known mean.

    my: number (optional)
        Known mean.

    Returns
    -------
    acc: Function
        Accumulator function.

    Examples
    --------
    > var accumulator = {{alias}}( 3 );
    > var r2 = accumulator()
    null
    > r2 = accumulator( 2.0, 1.0 )
    0.0
    > r2 = accumulator( -5.0, 3.14 )
    ~1.0
    > r2 = accumulator( 3.0, -1.0 )
    ~0.86
    > r2 = accumulator( 5.0, -9.5 )
    ~0.74
    > r2 = accumulator()
    ~0.74

    See Also
    --------

