Mercurial > forge
view main/miscellaneous/inst/chebyshevpoly.m @ 9602:ea1ae710473c octave-forge
miscellaneous: fix indentations, help text, use of print_usage, fix on demos, added simple input check
author | carandraug |
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date | Thu, 08 Mar 2012 16:23:48 +0000 |
parents | ba660b93032c |
children | d5e8b1f1c310 |
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## Copyright (C) 2007 Muthiah Annamalai <muthiah.annamalai@mavs.uta.edu> ## ## This program 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 program; if not, see <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {@var{coefs}=} chebyshevpoly (@var{kind},@var{order},@var{x}) ## ## Compute the coefficients of the Chebyshev polynomial, given the ## @var{order}. We calculate the Chebyshev polynomial using the recurrence ## relations, Tn+1(x) = (2*x*Tn(x) - Tn-1(x)). The @var{kind} can set to ## compute the first or second kind chebyshev polynomial. ## ## If the value @var{x} is specified, the polynomial is also evaluated, ## otherwise just the return the coefficients of the polynomial are returned. ## ## This is NOT the generalized Chebyshev polynomial. ## ## @end deftypefn function h=chebyshevpoly(kind,order,val) if nargin < 2, print_usage, endif h_prev=[0 1]; if kind == 1 h_now=[1 0]; elseif (kind == 2) h_now=[2 0]; else error('unknown kind'); endif if order == 0 h=h_prev; else h=h_now; endif for ord=2:order x=[];y=[]; if (length(h_now) < (1+ord)) x=0; endif y=zeros(1,(1+ord)-length(h_prev)); p1=[h_now, x]; p3=[y, h_prev]; h=2*p1 -p3; h_prev=h_now; h_now=h; endfor if nargin == 3 h=polyval(h,val); endif endfunction