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

    The correlation distance is defined as one minus the Pearson product-moment
    correlation coefficient and, thus, resides on the interval [0,2].

    If provided values, the accumulator function returns an updated sample
    correlation distance. If not provided values, the accumulator function
    returns the current sample correlation distance.

    If provided `NaN` or a value which, when used in computations, results in
    `NaN`, the accumulated value is `NaN` for all future invocations.

    Parameters
    ----------
    mx: number (optional)
        Known mean.

    my: number (optional)
        Known mean.

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

    Examples
    --------
    > var accumulator = {{alias}}();
    > var d = accumulator()
    null
    > d = accumulator( 2.0, 1.0 )
    1.0
    > d = accumulator( -5.0, 3.14 )
    ~2.0
    > d = accumulator()
    ~2.0

    See Also
    --------