Chebyshev differential matrices code not callable
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This is the code by tretfen (cheb.m):
% CHEB compute D = differentiation matrix, x = Chebyshev grid
function [D,x] = cheb(N)
if N==0, D=0; x=1; return, end
x = cos (pi*(0:N)/N)';
c = [2; ones(N-1,1); 2].*(-1).^(0:N)';
X = repmat(x,1,N+1);
dX = X-X';
D = (c*(1./c)')./(dX+(eye(N+1))); % off-diagonal entries
D = D - diag(sum(D')); % diagonal entries
2 Comments
Walter Roberson
on 19 Mar 2018
What parameter are you passing? What error message are you encountering?
Accepted Answer
Walter Roberson
on 19 Mar 2018
You have to go down to the command line and call the function passing in a non-negative integer. For example,
[differ_matrix, cheb_grid] = cheb(19)
3 Comments
Walter Roberson
on 19 Mar 2018
I stored the code you posted in the file cheb.m and then I went to the command line and there I commanded
[differ_matrix, cheb_grid] = cheb(19)
and I got back results.
You cannot run that function just by clicking on the green Run button: you must go to the command line to run it so that you can pass in a value for N.
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