--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imc/imc_stable.py	Fri May 27 14:24:59 2011 +0530
@@ -0,0 +1,36 @@
+#!/usr/bin/python
+# 10.9
+import os, sys
+sys.path += [os.getcwdu() + os.sep + ".." + os.sep + "python"]
+
+import scipy as sp
+from imcsplit import imcsplit
+from polyfuncs import poladd
+from zpowk import zpowk
+
+def imc_stable(B, A, k, alpha):
+    """ Designs Discrete Internal Model Controller
+    for transfer function z^{-k}B(z^{-1})/A(z^{-1})
+    Numerator and Denominator of IMC HQ are outputs
+    Controller is also given in R,S form. """
+    Kp, d, Bg, Bnmp, Bm = imcsplit(B, 1)
+    Bg = Kp * Bg
+    Bnmpr = Bnmp[::-1]
+    Bms = sum(Bm)
+    HiN = A
+    HiD = Bms * sp.convolve(Bg, Bnmpr)
+    k = k+d
+
+    zk, dzk = zpowk(k)
+    zk = sp.squeeze(zk)
+    Bf = 1-alpha
+    Af = sp.array([1, -alpha])
+    S = sp.convolve(Bf, A)
+    R1 = sp.convolve(Af, sp.convolve(Bnmpr, Bms))
+    R2 = sp.convolve(zk, sp.convolve(Bf, sp.convolve(Bnmp, Bm)))
+
+    R, dR = poladd(R1, len(R1)-1, -R2, len(R2)-1)
+    R = sp.squeeze(R)
+    R = sp.convolve(Bg, R)
+
+    return k, HiN, HiD, R, S