Mercurial > hg > octave-nkf
view scripts/polynomial/ppval.m @ 12174:db1f49eaba6b
whitespace fixes
author | John W. Eaton <jwe@octave.org> |
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date | Wed, 26 Jan 2011 23:49:42 -0500 |
parents | c792872f8942 |
children | 59e2460acae1 |
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## Copyright (C) 2000-2011 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{yi} =} ppval (@var{pp}, @var{xi}) ## Evaluate piecewise polynomial @var{pp} at the points @var{xi}. ## If @var{pp} is scalar-valued, the result is an array of the same shape as ## @var{xi}. ## Otherwise, the size of the result is @code{[pp.d, length(@var{xi})]} if ## @var{xi} is a vector, or @code{[pp.d, size(@var{xi})]} if it is a ## multi-dimensional array. If pp.orient is 1, the dimensions are permuted as ## in interp1, to ## @code{[pp.d, length(@var{xi})]} and @code{[pp.d, size(@var{xi})]} ## respectively. ## @seealso{mkpp, unmkpp, spline} ## @end deftypefn function yi = ppval (pp, xi) if (nargin != 2) print_usage (); endif if (! isstruct (pp)) error ("ppval: PP must be a structure"); endif ## Extract info. x = pp.x; P = pp.P; d = pp.d; k = size (P, 3); nd = size (P, 1); ## Determine resulting shape. if (d == 1) # scalar case yisz = size (xi); elseif (isvector (xi)) # this is special yisz = [d, length(xi)]; else # general yisz = [d, size(xi)]; endif ## Determine intervals. xi = xi(:); xn = numel (xi); idx = lookup (x, xi, "lr"); ## Offsets. dx = (xi - x(idx)).'; dx = dx(ones (1, nd), :); # spread (do nothing in 1D) ## Use Horner scheme. yi = P(:,idx,1); for i = 2:k; yi .*= dx; yi += P(:,idx,i); endfor ## Adjust shape. yi = reshape (yi, yisz); if (d != 1 && pp.orient == 1) ## Switch dimensions to match interp1 order. yi = shiftdim (yi, length (d)); endif endfunction