
{{alias}}( σ )
    Returns the expected value of a Rayleigh distribution.

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

    If provided `σ <= 0`, the function returns `NaN`.

    Parameters
    ----------
    σ: number
        Scale parameter.

    Returns
    -------
    out: number
        Expected value.

    Examples
    --------
    > var v = {{alias}}( 11.0 )
    ~13.786
    > v = {{alias}}( 4.5 )
    ~5.64

    See Also
    --------

