I have been struggling with ode45 for over a week and there is a weird convergence problem. So in my ode I have the following lines
B = kron(A, eye(3)); % size(A)=[n n] C = B*y; % size(y)=[3*n 1]
and then C will be used in later calculations
And the ode kept returning NAN, I set A = zeros(n,n) and the problem still persists
However, if I set C=zeros(3*n,1) the ode converges well.
To my understanding, by setting A = zeros(n,n) and running the above lines, no matter what value y is C will be equal to zeros(3*n,1), then why would it affect the convergence of the ode? Anyone familiar with the problem here?
Thanks a lot!
Hi, I guess the "y" vector contains a NaN, and as a consequence "C" contains also NaNs. This happen even if B is equal to zero (0 * nan = nan). You can verify this by adding the following sentence to your code:
if any(isnan(y)) disp('There is a nan in the vector y' ); end