From d7dcbdf32f7d55a002a9015b785fdadba0124f6c Mon Sep 17 00:00:00 2001
From: "Per.Andreas.Brodtkorb"
 <Per.Andreas.Brodtkorb@96a810ac-173e-11df-b9d6-e102a254d9bb>
Date: Thu, 4 Oct 2012 11:33:12 +0000
Subject: [PATCH] Added check on n

---
 pywafo/src/wafo/demos.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/pywafo/src/wafo/demos.py b/pywafo/src/wafo/demos.py
index 97b70f7..b2406c7 100644
--- a/pywafo/src/wafo/demos.py
+++ b/pywafo/src/wafo/demos.py
@@ -36,6 +36,9 @@ def magic(n):
            [30,  5, 34, 12, 14, 16],
            [ 4, 36, 29, 13, 18, 11]])
     '''
+    if (n<3):
+        raise ValueError('n must be greater than 2.')
+    
     if np.mod(n,2)==1: # odd order
         ix = np.arange(n) + 1
         J, I = np.meshgrid(ix, ix)
@@ -69,10 +72,10 @@ def magic(n):
             M[i][j] = M[i+p][j]
             M[i+p][j] = temp;
 
-            j=i;
-            temp=M[i+p][j]; 
-            M[i+p][j]=M[i][j]; 
-            M[i][j]=temp;
+            j=i
+            temp=M[i+p][j]
+            M[i+p][j]=M[i][j]
+            M[i][j]=temp
 
     return M