view toolbox/seqcheb.m @ 3:d24a00dabdc2 draft

Added first test and Makefile after figuring out how to!!! Also removed fontconfig rubbish created by a bug in my GNU/linux system. Note: review E.B. Davies's paper "Approximate Diagonalization" for tricky diagonalization problems.
author Antonio Pino Robles <data.script93@gmail.com>
date Fri, 15 May 2015 20:24:25 +0200
parents 8f23314345f4
children
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function x = seqcheb(n, k)
%SEQCHEB   Sequence of points related to Chebyshev polynomials.
%          X = SEQCHEB(N, K) produces a row vector of length N.
%          There are two choices:
%              K = 1:  zeros of T_N,         (the default)
%              K = 2:  extrema of T_{N-1},
%          where T_k is the Chebsyhev polynomial of degree k.

if nargin == 1, k = 1; end

if k == 1                     %  Zeros of T_n
   i = 1:n; j = .5*ones(1,n);
   x = cos( (i-j) * (pi/n) );
elseif k == 2                 %  Extrema of T_(n-1)
   i = 0:n-1;
   x = cos( i * (pi/(n-1)) );
end