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comparison scripts/polynomial/ppjumps.m @ 9976:702b998698ea

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implement ppder, ppint, ppjmups
author Jaroslav Hajek <highegg@gmail.com>
date Sun, 13 Dec 2009 13:18:27 +0100
parents
children be55736a0783
comparison
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9975:14ed68363284 9976:702b998698ea
1 ## Copyright (C) 2008, 2009 VZLU Prague, a.s., Czech Republic
2 ##
3 ## This file is part of Octave.
4 ##
5 ## Octave is free software; you can redistribute it and/or modify
6 ## it under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or
8 ## (at your option) any later version.
9 ##
10 ## This program is distributed in the hope that it will be useful,
11 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 ## GNU General Public License for more details.
14 ##
15 ## You should have received a copy of the GNU General Public License
16 ## along with this software; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
18
19 ## -*- texinfo -*-
20 ## @deftypefn{Function File} {ppd =} ppjumps (pp)
21 ## Evaluates the boundary jumps of a piecewise polynomial.
22 ## If there are n intervals, and the dimensionality of pp is d,
23 ## the resulting array has dimensions @code{[d, n-1]}.
24 ## @end deftypefn
25
26 function jumps = ppjumps (pp)
27 if (nargin != 1)
28 print_usage ();
29 endif
30 if (! isstruct (pp))
31 error ("ppjumps: expects a pp structure");
32 endif
33
34 ## Extract info.
35 x = pp.x;
36 P = pp.P;
37 d = pp.d;
38 [nd, n, k] = size (P);
39
40 ## Offsets.
41 dx = diff (x(1:n)).';
42 dx = dx(ones (1, nd), :); # spread (do nothing in 1D)
43
44 ## Use Horner scheme to get limits from the left.
45 llim = P(:,1:n-1,1);
46 for i = 2:k;
47 llim .*= dx;
48 llim += P(:,1:n-1,i);
49 endfor
50
51 rlim = P(:,2:n,k); # limits from the right
52 jumps = reshape (rlim - llim, [d, n-1]);
53
54 endfunction