--- a/inst/deriche.m
+++ b/inst/deriche.m
@@ -1,8 +1,10 @@
 # $Id$
-function [V, H] = deriche(img, alpha)
-# OUTPUT 
-#  V -> vertical gradient
-#  H -> horizontal gradient
+function result = deriche(img, alpha, method)
+# OUTPUT
+# method  0 (default)
+#    magnitude of gradient
+# method = 1 
+#    vector gradient (last index 1 for H, 2 for V)
 # 
 # INPUT
 #  img    -> input image (as matrix of doubles) 
@@ -33,6 +35,9 @@
 # version:  0.1
 #
 ## $Log$
+## Revision 1.2  2006/12/08 06:41:30  cocus
+## interface changed to match cc implementation. (returns magnitude by default)
+##
 ## Revision 1.1  2006/12/03 10:53:14  cocus
 ## initial m-file implementetaion.
 ##
@@ -55,6 +60,10 @@
   alpha = 1.0
 end
 
+if nargin < 3
+  method = 0
+end
+
    a   =  -(1-exp(-alpha))^2;
    b1 =  -2*exp(-alpha);
    b2 = exp(-2*alpha);
@@ -71,9 +80,8 @@
   g_h1 = zeros(n,m);
   g_h2 = zeros(n,m);
   g_hv = zeros(n,m);
-  H = zeros(n,m);
-  V = zeros(n,m);  
-  
+  result = zeros(n,m,2);
+    
   for k=3:m
     g_v1(:,k) = img(:, k-1) - b1 * g_v1(:,k-1)- b2 * g_v1(:,k-2);
   end;
@@ -91,7 +99,7 @@
      g_h1(k,:) = a2 * g_hv(k+1,:) + a3 * g_hv(k+2,:) - b1 *  g_h2(k+1,:) - b2 * g_h2(k+2,:);
   end;
 
-H = g_h1 + g_h2;
+result(:,:,1) = g_h1 + g_h2;
   
   for k=3:n
     g_v1(k,:) = img(k-1,:) - b1 * g_v1(k-1,:)- b2 * g_v1(k-2,:);
@@ -110,9 +118,10 @@
      g_h1(:,k) = a2 * g_hv(:,k+1) + a3 * g_hv(:,k+2) - b1 *  g_h2(:,k+1) - b2 * g_h2(:,k+2);
   end;
 
-V = g_h1 + g_h2;
+result(:,:,2) = g_h1 + g_h2;
+
+if (method == 0)
+  result = sqrt(result(:,:,1).*result(:,:,1)+result(:,:,2).*result(:,:,2));
+end
 
 
-
-
-