1 #!/usr/bin/python 

     2 # Both Rc and Sc have to be degree one polynomials

     3 

     4 def pd(Rc,Sc,Ts):

     5     K = (Sc[0]+Sc[1])/(1+Rc[1])

     6     N = (Sc[1]-Sc[0]*Rc[1])/Rc[1]/(Sc[0]+Sc[1])

     7     taudbyN = -Ts*Rc[1]/(1+Rc[1])

     8     taud = taudbyN * N

     9     return K, taud, N