
{{alias}}( x, α, β )
    Evaluates the probability density function (PDF) for an inverse gamma
    distribution with shape parameter `α` and scale parameter `β` at a value
    `x`.

    If `α <= 0` or `β <= 0`, the function returns `NaN`.

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

    Parameters
    ----------
    x: number
        Input value.

    α: number
        Shape parameter.

    β: number
        Scale parameter.

    Returns
    -------
    out: number
        Evaluated PDF.

    Examples
    --------
    > var y = {{alias}}( 2.0, 0.5, 1.0 )
    ~0.121
    > y = {{alias}}( 0.2, 1.0, 1.0 )
    ~0.168
    > y = {{alias}}( -1.0, 4.0, 2.0 )
    0.0

    > y = {{alias}}( NaN, 1.0, 1.0 )
    NaN
    > y = {{alias}}( 0.0, NaN, 1.0 )
    NaN
    > y = {{alias}}( 0.0, 1.0, NaN )
    NaN

    // Negative shape parameter:
    > y = {{alias}}( 2.0, -1.0, 1.0 )
    NaN

    // Negative scale parameter:
    > y = {{alias}}( 2.0, 1.0, -1.0 )
    NaN


{{alias}}.factory( α, β )
    Returns a function for evaluating the probability density function (PDF)
    of an inverse gamma distribution with shape parameter `α` and scale
    parameter `β`.

    Parameters
    ----------
    α: number
        Shape parameter.

    β: number
        Scale parameter.

    Returns
    -------
    pdf: Function
        Probability density function (PDF).

    Examples
    --------
    > var myPDF = {{alias}}.factory( 6.0, 7.0 );
    > var y = myPDF( 2.0 )
    ~0.231

    See Also
    --------

