{{alias}}( x, s[, regularized[, upper]] )
    Computes the regularized incomplete gamma function.

    The `regularized` and `upper` parameters specify whether to evaluate the
    non-regularized and/or upper incomplete gamma functions, respectively.

    If provided `x < 0` or `s <= 0`, the function returns `NaN`.

    If provided `NaN` as any argument, the function returns `NaN`.

    Parameters
    ----------
    x: number
        First function parameter.

    s: number
        Second function parameter.

    regularized: boolean (optional)
        Boolean indicating whether the function should evaluate the regularized
        or non-regularized incomplete gamma function. Default: `true`.

    upper: boolean (optional)
        Boolean indicating whether the function should return the upper tail of
        the incomplete gamma function. Default: `false`.

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

    Examples
    --------
    > var y = {{alias}}( 6.0, 2.0 )
    ~0.9826
    > y = {{alias}}( 1.0, 2.0, true, true )
    ~0.7358
    > y = {{alias}}( 7.0, 5.0 )
    ~0.8270
    > y = {{alias}}( 7.0, 5.0, false )
    ~19.8482
    > y = {{alias}}( NaN, 2.0 )
    NaN
    > y = {{alias}}( 6.0, NaN )
    NaN

    See Also
    --------