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diff --git a/octave_packages/m/set/intersect.m b/octave_packages/m/set/intersect.m
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+## Copyright (C) 2000-2012 Paul Kienzle
+## Copyright (C) 2008-2009 Jaroslav Hajek
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {} intersect (@var{a}, @var{b})
+## @deftypefnx {Function File} {[@var{c}, @var{ia}, @var{ib}] =} intersect (@var{a}, @var{b})
+##
+## Return the elements in both @var{a} and @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.
+## @var{a}, @var{b} may be cell arrays of string(s).
+##
+## Return index vectors @var{ia} and @var{ib} such that @code{a(ia)==c} and
+## @code{b(ib)==c}.
+##
+## @end deftypefn
+## @seealso{unique, union, setxor, setdiff, ismember}
+
+function [c, ia, ib] = intersect (a, b, varargin)
+
+  if (nargin < 2 || nargin > 3)
+    print_usage ();
+  endif
+
+  [a, b] = validargs ("intersect", a, b, varargin{:});
+
+  if (isempty (a) || isempty (b))
+    c = ia = ib = [];
+  else
+    ## form a and b into sets
+    if (nargout > 1)
+      [a, ja] = unique (a, varargin{:});
+      [b, jb] = unique (b, varargin{:});
+    else
+      a = unique (a, varargin{:});
+      b = unique (b, varargin{:});
+    endif
+
+    if (nargin > 2)
+      c = [a; b];
+      [c, ic] = sortrows (c);
+      ii = find (all (c(1:end-1,:) == c(2:end,:), 2));
+      c = c(ii,:);
+      len_a = rows (a);
+    else
+      c = [a(:); b(:)];
+      [c, ic] = sort (c);               ## [a(:);b(:)](ic) == c
+      if (iscellstr (c))
+        ii = find (strcmp (c(1:end-1), c(2:end)));
+      else
+        ii = find (c(1:end-1) == c(2:end));
+      endif
+      c = c(ii);
+      len_a = length (a);
+    endif
+
+    if (nargout > 1)
+      ia = ja(ic(ii));                  ## a(ia) == c
+      ib = jb(ic(ii+1) - len_a);        ## b(ib) == c
+    endif
+
+    if (nargin == 2 && (size (b, 1) == 1 || size (a, 1) == 1))
+      c = c.';
+    endif
+  endif
+
+endfunction
+
+
+%!# Test the routine for index vectors ia and ib
+%!test
+%! a = [3 2 4 5 7 6 5 1 0 13 13];
+%! b = [3 5 12 1 1 7];
+%! [c,ia,ib] = intersect(a,b);
+%! assert(c,[1 3 5 7]);
+%! assert(ia,[8 1 7 5]);
+%! assert(ib,[5 1 2 6]);
+%! assert(a(ia),c);
+%! assert(b(ib),c);
+%!test
+%! a = [1,1,2;1,4,5;2,1,7];
+%! b = [1,4,5;2,3,4;1,1,2;9,8,7];
+%! [c,ia,ib] = intersect(a,b,'rows');
+%! assert(c,[1,1,2;1,4,5]);
+%! assert(ia,[1;2]);
+%! assert(ib,[3;1]);
+%! assert(a(ia,:),c);
+%! assert(b(ib,:),c);
+%!test
+%! a = [1 1 1 2 2 2];
+%! b = [1 2 3 4 5 6];
+%! c = intersect(a,b);
+%! assert(c, [1,2]);
+%!test
+%! a = [1 2 3 4; 5 6 7 8; 9 10 11 12];
+%! [b, ia, ib] = intersect(a, a, "rows");
+%! assert(b, a);
+%! assert(ia, [1:3]');
+%! assert(ib, [1:3]');