function y = ChebyshevEval(n,x);
%
% Evaluate Chebyshev polynomails up to degree n for a given x.
%
% written by Ming Gu for Math128B, Spring 2009
%
y = ones(length(x),n+1);
if (n==0)
    return;
end
y(:,2) = x;
if (n==1)
    return;
end
tx = 2*x;
for k=3:n+1
    y(:,k) = tx.*y(:,k-1)-y(:,k-2);
end