{{alias}}( n, x )
    Evaluates the polygamma function of order `n`; i.e., the (n+1)th derivative
    of the natural logarithm of the gamma function.

    If `n` is not a nonnegative integer, the function returns `NaN`.

    If `x` is zero or a negative integer, the function returns `NaN`.

    If provided `NaN` as either parameter, the function returns `NaN`.

    Parameters
    ----------
    n: integer
        Derivative order.

    x: number
        Input value.

    Returns
    -------
    y: number
        Function value.

    Examples
    --------
    > var v = {{alias}}( 3, 1.2 )
    ~3.245
    > v = {{alias}}( 5, 1.2 )
    ~41.39
    > v = {{alias}}( 3, -4.9 )
    ~60014.239
    > v = {{alias}}( -1, 5.3 )
    NaN
    > v = {{alias}}( 2, -1.0 )
    Infinity

    See Also
    --------