function a = cheby_van3 ( n ) %*****************************************************************************80 % %% CHEBY_VAN3 returns the Chebyshev Vandermonde-like matrix. % % Formula: % % A(I,J) = cos ( (I-1) * (J-1/2) * PI / N ) % % Example: % % N = 4 % % 1 1 1 1 % COS( PI/8) COS(3*PI/8) COS( 5*PI/8) COS( 7*PI/8) % COS(2*PI/8) COS(6*PI/8) COS(10*PI/8) COS(14*PI/8) % COS(3*PI/8) COS(9*PI/8) COS(15*PI/8) COS(21*PI/8) % % Properties: % % A is generally not symmetric: A' /= A. % % A is "almost" orthogonal. A * A' = a diagonal matrix. % % The entries of A are based on the zeros of the Chebyshev polynomial T(n). % % Licensing: % % This code is distributed under the GNU LGPL license. % % Modified: % % 28 September 2007 % % Author: % % John Burkardt % % Parameters: % % Input, integer N, the order of A. % % Output, real A(N,N), the matrix. % for i = 1 : n for j = 1 : n angle = ( i - 1 ) * ( 2 * j - 1 ) * pi / ( 2 * n ); a(i,j) = cos ( angle ); end end return end