--- /dev/null
+## 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