def qart(data,a=0.0,f=0.0):
    """
    Scale Quad Artifacts

    Functional Form:
        R' = R
        I' = (1+a)*I + f*R

    Parameters:

    * data  Array of spectral data.
    * a     Amplitude adjustment.
    * f     Phase adjustment.

    """
    data.imag = (1+a)*data.imag + f*data.real
    return data