{{alias}}( x )
     Tests if a double-precision floating-point numeric value is `NaN`.

    Parameters
    ----------
    x: number
        Value to test.

    Returns
    -------
    bool: boolean
        Boolean indicating whether the value is `NaN`.

    Examples
    --------
    > var bool = {{alias}}( NaN )
    true
    > bool = {{alias}}( 7.0 )
    false

    See Also
    --------