diff --git a/ss2013/1_Web Mining/Uebungen/4_Uebung/code/confusion_matrix.py b/ss2013/1_Web Mining/Uebungen/4_Uebung/code/confusion_matrix.py
index 52f7fb8c..1213b4d3 100644
--- a/ss2013/1_Web Mining/Uebungen/4_Uebung/code/confusion_matrix.py	
+++ b/ss2013/1_Web Mining/Uebungen/4_Uebung/code/confusion_matrix.py	
@@ -48,13 +48,21 @@ def accuracy():
     global document_count
     i = 0
     ok_recognized = 0
+    wrong_recognized = 0
     for conf in conf_matr:
-        ok_recognized += conf[i]
+        j = 0
+        for c in conf:
+            if i == j:
+                ok_recognized += c
+            else:
+                wrong_recognized += c    
+            j += 1
+        
         i += 1
 
     #print ok_recognized
     #print document_count        
-    accuracy = float(ok_recognized) / float(document_count)
+    accuracy = float(ok_recognized) / float(wrong_recognized)
     
 def prec():
     #per class -> positive matches / alle matches auf class