--- a/scripts/set/setdiff.m
+++ b/scripts/set/setdiff.m
@@ -19,34 +19,65 @@
 
 ## -*- texinfo -*-
 ## @deftypefn {Function File} {} setdiff (@var{a}, @var{b})
-## Return the elements in @var{a} but not in @var{b}, sorted in
+## @deftypefnx {Function File} {} setdiff(@var{a}, @var{b}, "rows")
+## Return the elements in @var{a} that are not in @var{b}, sorted in
 ## ascending order.  If @var{a} and @var{b} are both column vectors
 ## return a column vector, otherwise return a row vector.
+##
+## Given the optional third argument @samp{"rows"}, return the rows in
+## @var{a} that are not in @var{b}, sorted in ascending order by rows.
 ## @seealso{unique, union, intersect, setxor, ismember}
 ## @end deftypefn
 
 ## Author: Paul Kienzle
 ## Adapted-by: jwe
 
-function c = setdiff (a, b)
+function c = setdiff (a, b, byrows)
+
+  if (nargin < 2 || nargin > 3)
+    usage ("setdiff (a, b) or setdiff (a, b, \"rows\")");
+  endif
 
-  if (nargin != 2)
-    usage ("setdiff (a, b)");
+  if (nargin == 3)
+    if (! strcmpi (byrows, "rows"))
+      error ("expecting third argument to be \"rows\"");
+    else
+      byrows = true;
+    endif
+  else
+    byrows = false;
   endif
 
-  c = unique (a);
-  if (! isempty (c) && ! isempty (b))
-    ## Form a and b into combined set.
-    b = unique (b);
-    [dummy, idx] = sort ([c(:); b(:)]);
-    ## Eliminate those elements of a that are the same as in b.
-    n = length (dummy);
-    c(idx(find (dummy(1:n-1) == dummy(2:n)))) = [];
-    ## Reshape if necessary.
-    if (size (c, 1) != 1 && size (b, 1) == 1)
-      c = c.';
+  if (byrows)
+    c = unique (a, "rows");
+    if (! isempty (c) && ! isempty (b))
+      ## Form a and b into combined set.
+      b = unique (b, "rows");
+      [dummy, idx] = sortrows ([c; b]);
+      ## Eliminate those elements of a that are the same as in b.
+      n = length (dummy);
+      c(idx(find (dummy(1:n-1) == dummy(2:n))), :) = [];
+    endif
+  else
+    c = unique (a);
+    if (! isempty (c) && ! isempty (b))
+      ## Form a and b into combined set.
+      b = unique (b);
+      [dummy, idx] = sort ([c(:); b(:)]);
+      ## Eliminate those elements of a that are the same as in b.
+      n = length (dummy);
+      c(idx(find (dummy(1:n-1) == dummy(2:n)))) = [];
+      ## Reshape if necessary.
+      if (size (c, 1) != 1 && size (b, 1) == 1)
+	c = c.';
+      endif
     endif
   endif
-
+  
 endfunction
   
+%!assert(setdiff(["bb";"zz";"bb";"zz"],["bb";"cc";"bb"],"rows"), "zz")
+%!assert(setdiff(["b";"z";"b";"z"],["b";"c";"b"],"rows"), "z")
+%!assert(setdiff(["b";"z";"b";"z"],["b";"c";"b"]), "z")
+%!assert(setdiff([1, 1; 2, 2; 3, 3; 4, 4], [1, 1; 2, 2; 4, 4], "rows"), [3 3])
+%!assert(setdiff([1; 2; 3; 4], [1; 2; 4], "rows"), 3)