def METHOD_NAME(rqcqi):
    f0=1000.
    Qi= 1000.
    Qe = rqcqi*Qi
    Q = 1./(1./Qi+1./Qe)
    df = f0/Q
    f = np.linspace(f0-5*df,f0+5*df,10001)
    p0 = (1.,f0,Q,Qe,df,1.)
    param = S21p0i2params(f,p0)
    return np.abs(disp_hanger_S21_complex(param))