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+## Copyright (C) 2007  David Bateman
+##
+## 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 2, 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, write to the Free
+## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+## 02110-1301, USA.
+
+## -*- texinfo -*-
+## @deftypefn {Loadable Function} {@var{idx} =} dsearchn (@var{x}, @var{tri}, @var{xi})
+## @deftypefnx {Loadable Function} {@var{idx} =} dsearchn (@var{x}, @var{tri}, @var{xi}, @var{outval})
+## @deftypefnx {Loadable Function} {@var{idx} =} dsearchn (@var{x}, @var{xi})
+## @deftypefnx {Loadable Function} {[@var{idx}, @var{d}] =} dsearchn (@dots{})
+## Returns the index @var{idx} or the closest point in @var{x} to the elements
+## @var{xi}. If @var{outval} is supplied, then the values of @var{xi} that are
+## not contained within one of the simplicies @var{tri} are set to 
+## @var{outval}. Generally, @var{tri} is returned from @code{delaunayn 
+## (@var{x})}.
+## @seealso{dsearch, tsearch}
+## @end deftypefn
+
+function [idx, d] = dsearchn (x, t, xi, outval)
+  if (nargin < 2 || nargin > 4)
+    print_usage ();
+  endif
+
+  if (nargin == 2)
+    [idx, d] = __dsearchn__ (x, t);
+  else
+    [idx, d] = __dsearchn__ (x, xi);
+    if (nargin == 4)
+      idx2 = isnan (tsearchn (x, t, xi));
+      idx(idx2) = outval;
+      d(idx2) = outval;
+    endif
+  endif
+endfunction
+
+%!shared x, tri
+%! x = [-1,-1;-1,1;1,-1]; 
+%! tri = [1,2,3]; 
+%!assert (dsearchn(x,tri,[1,1/3]), 3);
+%!assert (dsearchn(x,tri,[1,1/3],NaN), NaN);
+%!assert (dsearchn(x,tri,[1,1/3],NA), NA);
+%!assert (dsearchn(x,tri,[1/3,1]), 2);
+%!assert (dsearchn(x,tri,[1/3,1],NaN), NaN);
+%!assert (dsearchn(x,tri,[1/3,1],NA), NA);