{{alias}}( x )
    Evaluates the natural logarithm of `1+exp(x)`.

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

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

    Examples
    --------
    > var y = {{alias}}( -10.0 )
    ~0.000045
    > y = {{alias}}( 0.0 )
    ~0.693147
    > y = {{alias}}( 5.0 )
    ~5.006715
    > y = {{alias}}( 34.0 )
    34.0
    > y = {{alias}}( NaN )
    NaN

    See Also
    --------