def ABCDFrequencyList_to_YFrequencyList(ABCD_frequency_list):
    """ Converts ABCD parameters into Y-parameters. ABCD-parameters should be in the form [[f,A,B,C,D],...]
    Returns data in the form
    [[f,Y11,Y12,Y21,Y22],...]
    """
    y_frequency_list=[]
    for row in ABCD_frequency_list[:]:
        [frequency,A,B,C,D]=row
        Y11=D/B
        Y12=(B*C-A*D)/B
        Y21=-1/B
        Y22=A/B
        y_frequency_list.append([frequency,Y11,Y12,Y21,Y22])
    return y_frequency_list