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diff --git a/octave_packages/m/polynomial/unmkpp.m b/octave_packages/m/polynomial/unmkpp.m
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+## Copyright (C) 2000-2012 Paul Kienzle
+##
+## 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} {[@var{x}, @var{p}, @var{n}, @var{k}, @var{d}] =} unmkpp (@var{pp})
+##
+## Extract the components of a piecewise polynomial structure @var{pp}.
+## The components are:
+##
+## @table @asis
+## @item @var{x}
+## Sample points.
+##
+## @item @var{p}
+## Polynomial coefficients for points in sample interval.  @code{@var{p}
+## (@var{i}, :)} contains the coefficients for the polynomial over
+## interval @var{i} ordered from highest to lowest.  If @code{@var{d} >
+## 1}, @code{@var{p} (@var{r}, @var{i}, :)} contains the coefficients for
+## the r-th polynomial defined on interval @var{i}.
+##
+## @item @var{n}
+## Number of polynomial pieces.
+##
+## @item @var{k}
+## Order of the polynomial plus 1.
+##
+## @item @var{d}
+## Number of polynomials defined for each interval.
+## @end table
+##
+## @seealso{mkpp, ppval, spline, pchip}
+## @end deftypefn
+
+function [x, P, n, k, d] = unmkpp (pp)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+  if (! (isstruct (pp) && isfield (pp, "form") && strcmp (pp.form, "pp")))
+    error ("unmkpp: PP must be a piecewise polynomial structure");
+  endif
+  x = pp.breaks;
+  P = pp.coefs;
+  n = pp.pieces;
+  k = pp.order;
+  d = pp.dim;
+
+endfunction
+
+
+%!test
+%! b = 1:3;
+%! c = 1:24;
+%! pp = mkpp (b,c);
+%! [x, P, n, k, d] = unmkpp (pp);
+%! assert (x, b);
+%! assert (P, reshape (c, [2 12]));
+%! assert (n, 2);
+%! assert (k, 12);
+%! assert (d, 1);
+
+%% Test input validation
+%!error unmkpp ()
+%!error unmkpp (1,2)
+%!error <piecewise polynomial structure> unmkpp (1)
+%!error <piecewise polynomial structure> unmkpp (struct ("field1", "pp"))
+%!error <piecewise polynomial structure> unmkpp (struct ("form", "not_a_pp"))
+