
{{alias}}( x )
    Computes the half-value versed cosine.

    The half-value versed cosine is defined as `(1 + cos(x)) / 2`.

    Parameters
    ----------
    x: number
        Input value (in radians).

    Returns
    -------
    y: number
        Half-value versed cosine.

    Examples
    --------
    > var y = {{alias}}( 3.14 )
    ~0.0
    > y = {{alias}}( -4.2 )
    ~0.2549
    > y = {{alias}}( -4.6 )
    ~0.4439
    > y = {{alias}}( 9.5 )
    ~0.0014
    > y = {{alias}}( -0.0 )
    1.0

    See Also
    --------

