diff --git a/scripts/set/setdiff.m b/scripts/set/setdiff.m
--- a/scripts/set/setdiff.m
+++ b/scripts/set/setdiff.m
@@ -31,7 +31,7 @@
 ## Author: Paul Kienzle
 ## Adapted-by: jwe
 
-function c = setdiff (a, b, byrows_arg)
+function [c,i] = setdiff (a, b, byrows_arg)
 
   if (nargin < 2 || nargin > 3)
     print_usage ();
@@ -78,7 +78,13 @@ function c = setdiff (a, b, byrows_arg)
       endif
     endif
   endif
-  
+
+  [sorta, idxa] = sort (a);
+  idx = idxa (find (all (repmat (sorta(:)',size(c,1)*size(c,2),1)-...
+			 repmat (c(:), 1, size(a,1)*size(a,2))) == 0));
+  [y,iy] = unique (a(idx));
+  i = reshape (idx(iy), size(c,1), length(idx(iy))/size(c,1));
+
 endfunction
   
 %!assert(setdiff(["bb";"zz";"bb";"zz"],["bb";"cc";"bb"],"rows"), "zz")