update packages

[CreaPhase.git] / octave_packages / m / polynomial / ppint.m

diff --git a/octave_packages/m/polynomial/ppint.m b/octave_packages/m/polynomial/ppint.m
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+## Copyright (C) 2008-2012 VZLU Prague, a.s., Czech Republic
+##
+## 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.
+##
+## This program 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 this software; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {@var{ppi} =} ppint (@var{pp})
+## @deftypefnx {Function File} {@var{ppi} =} ppint (@var{pp}, @var{c})
+## Compute the integral of the piecewise polynomial struct @var{pp}.
+## @var{c}, if given, is the constant of integration.
+## @seealso{mkpp, ppval, ppder}
+## @end deftypefn
+
+function ppi = ppint (pp, c)
+  if (nargin < 1 || nargin > 2)
+    print_usage ();
+  endif
+  if (! (isstruct (pp) && strcmp (pp.form, "pp")))
+    error ("ppint: PP must be a structure");
+  endif
+
+  [x, p, n, k, d] = unmkpp (pp);
+  p = reshape (p, [], k);
+
+  ## Get piecewise antiderivatives
+  pi = p / diag (k:-1:1);
+  k += 1;
+  if (nargin == 1)
+    pi(:, k) = 0;
+  else
+    pi(:, k) = repmat (c(:), n, 1);
+  endif
+
+  ppi = mkpp (x, pi, d);
+
+  tmp = -cumsum (ppjumps (ppi), length (d) + 1);
+  ppi.coefs(prod(d)+1:end, k) = tmp(:);
+
+endfunction
+
+%!shared x,y,pp,ppi
+%! x=0:8;y=[ones(size(x));x+1];pp=spline(x,y);
+%! ppi=ppint(pp);
+%!assert(ppval(ppi,x),[x;0.5*x.^2+x],1e-14)
+%!assert(ppi.order,5)