--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python/seshft.py	Fri May 27 14:24:59 2011 +0530
@@ -0,0 +1,38 @@
+#!/usr/bin/python
+# given A and B arrays, returns C = [<-A-> 0
+#                                    0  <-B->] with B shifted east by N cols
+
+import pylab as pl
+from scipy import signal
+
+def seshft(A, B, N):
+    Arows, Acols = pl.atleast_2d(A).shape
+    Brows, Bcols = pl.atleast_2d(B).shape
+
+    if N>=0:
+        n = Arows+Brows
+        m = max(Acols, Bcols+N)
+        C = pl.zeros((n, m))
+        C[:Arows, :Acols] = A
+        C[Arows:, N:N+Bcols] = B
+
+    else:
+        N = -N
+        n = Arows+Brows
+        m = max(Acols+N, Bcols)
+        C = pl.zeros((n, m))
+        C[:Arows, N:N+Arows] = A
+        C[Arows:, :Bcols] = B
+
+    return C
+
+if __name__== "__main__":
+    a = "A = pl.eye(3)"
+    b = "B = pl.eye(10)"
+    n = "N = 0"
+    exec(a)
+    exec(b)
+    exec(n)
+    print a, b, n
+    C = seshft(A, B, N)
+    print C