Mercurial > octave-nkf
view scripts/polynomial/ppder.m @ 20643:d6d04088ac9e
nbininv.m: Increase speed (85X) and accuracy of function (bug #34363).
* nbininv.m: Call new function scalar_nbininv to calculate nbininv for scalar.
If there are still uncalculated values then call bin_search_nbininv. Call
bin_search_nbininv directly for vectors. Add more BIST tests.
* nbininv.m (scalar_binoinv): New subfunction to calculate nbininv for scalar x.
Stops when x > 1000.
* nbininv.m (bin_search_nbininv): New subfunction to do binary search for nbininv.
author | Lachlan Andrew <lachlanbis@gmail.com> |
---|---|
date | Sun, 11 Oct 2015 20:33:37 -0700 |
parents | f1d0f506ee78 |
children |
line wrap: on
line source
## Copyright (C) 2008-2015 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 Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {ppd =} ppder (pp) ## @deftypefnx {Function File} {ppd =} ppder (pp, m) ## Compute the piecewise @var{m}-th derivative of a piecewise polynomial ## struct @var{pp}. ## ## If @var{m} is omitted the first derivative is calculated. ## @seealso{mkpp, ppval, ppint} ## @end deftypefn function ppd = ppder (pp, m = 1) if (nargin < 1 || nargin > 2) print_usage (); endif if (! (isstruct (pp) && strcmp (pp.form, "pp"))) error ("ppder: PP must be a structure"); endif [x, p, n, k, d] = unmkpp (pp); if (k - m <= 0) x = [x(1) x(end)]; pd = zeros (prod (d), 1); else f = k : -1 : 1; ff = bincoeff (f, m + 1) .* factorial (m + 1) ./ f; k -= m; pd = p(:,1:k) * diag (ff(1:k)); endif ppd = mkpp (x, pd, d); endfunction %!shared x,y,pp,ppd %! x = 0:8; %! y = [x.^2; x.^3+1]; %! pp = spline (x, y); %! ppd = ppder (pp); %!assert (ppval (ppd, x), [2*x; 3*x.^2], 1e-14) %!assert (ppd.order, 3) %! ppd = ppder (pp, 2); %!assert (ppval (ppd, x), [2*ones(size (x)); 6*x], 1e-14) %!assert (ppd.order, 2) %! ppd = ppder (pp, 3); %!assert (ppd.order, 1) %!assert (ppd.pieces, 8) %!assert (size (ppd.coefs), [16, 1]) %! ppd = ppder (pp, 4); %!assert (ppd.order, 1) %!assert (ppd.pieces, 1) %!assert (size (ppd.coefs), [2, 1]) %!assert (ppval (ppd,x), zeros (size (y)), 1e-14)