Output sizes for MATALB function block in Simulink.

Hi,

I would like to use Simulink to do some calculation. In Simulink, there is a constant block sending the input, passing to the MATLAB function, and display the output in a Display block. The function has been tested and worked well on MATLAB, but an error occur in simulink:

Simulink does not have enough information to determine output sizes for this block. If you think the errors below are inaccurate, try specifying types for the block inputs and/or sizes for the block outputs.

%MATLAB function
function y = fcn(u)

B = 0;
A = 100*(10/u-1); 

F=@(x)[6*exp(-39*10^(-3)*x)+230*exp(-6*10^(-5)*x)-A];

B = fsolve(F,0,optimoptions('fsolve','Algorithm','levenberg-marquardt'));

y = B;

Any suggestion will be appreciated. Thank you.

Answer 1

[Fangjun Jiang]

It is interesting that you want to do this. Does the solution "B" always exist? How many solutions are there and are there always the same number of solutions?

Anyway, those questions are related to the error message. You could try to resolve it this way. In the M Editor, click menu button "Edit Data" and set the size of "B" or "y" or both.

[gdz]

Thank you for the reply. It solves my problem.

The B does not exist all the time, so i will set a range for the input u. There are alway one solution and the solution will be the same.