Mercurial > octave
view scripts/polynomial/ppjumps.m @ 31200:075443476dfb stable
nextpow2.m: Add bug number tag to regression BIST tests (bug #62947)
* nextpow2.m: Add '<*62947>' to BIST tests for bug #62947.
author | Rik <rik@octave.org> |
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date | Wed, 24 Aug 2022 08:55:14 -0700 |
parents | 796f54d4ddbf |
children | 597f3ee61a48 |
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######################################################################## ## ## Copyright (C) 2008-2022 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{jumps} =} ppjumps (@var{pp}) ## Evaluate the boundary jumps of a piecewise polynomial. ## ## If there are @math{n} intervals, and the dimensionality of @var{pp} is ## @math{d}, the resulting array has dimensions @code{[d, n-1]}. ## @seealso{mkpp} ## @end deftypefn function jumps = ppjumps (pp) if (nargin < 1) print_usage (); endif if (! (isstruct (pp) && strcmp (pp.form, "pp"))) error ("ppjumps: PP must be a structure"); endif ## Extract info. [x, P, n, k, d] = unmkpp (pp); nd = length (d) + 1; ## Offsets. dx = diff (x(1:n)); dx = repmat (dx, [prod(d), 1]); dx = reshape (dx, [d, n-1]); dx = shiftdim (dx, nd - 1); ## Use Horner scheme. if (k>1) llim = shiftdim (reshape (P(1:(n-1) * prod (d), 1), [d, n-1]), nd - 1); endif for i = 2 : k llim .*= dx; llim += shiftdim (reshape (P(1:(n-1) * prod (d), i), [d, n-1]), nd - 1); endfor rlim = shiftdim (ppval (pp, x(2:end-1)), nd - 1); jumps = shiftdim (rlim - llim, 1); endfunction %!test %! p = [1 6 11 6]; %! x = linspace (5, 6, 4); %! y = polyval (p, x); %! pp = spline (x, y); %! jj = ppjumps (pp); %! assert (jj, [0 0], eps); %!test %! breaks = [0 1 2]; %! pp1 = poly (-[1 2 3]); %! pp2 = poly (-([1 2 3]+1)); %! pp = mkpp (breaks, [pp1;pp2]); %! assert (ppjumps (pp), 0, eps); %!test %! breaks = [0 1 2]; %! pp1 = poly (-[1 2 3]); %! pp2 = poly (([1 2 3]+1)); %! pp = mkpp (breaks, [pp1;pp2]); %! j = - 2 * polyval (pp1, 1); %! assert (ppjumps (pp), j, eps);