How can I use a function handle in Simulink "matlab function" block?

Hello,

I am trying to simulate this first order function

*function [f,h] = Model_First_order(u,deltat)

f=@(x)[x(1)+deltat*(-x(2)*x(1)+u(1)); x(2)]; h=@(x)x(1);*

using the function handle in Simulink Matlab function block. But as I try to simulate it, it gives me an error that

Anonymous functions are not supported for code generation. Function 'Model_first_order' (#23.313.314), line 21, column 3: "@" Launch diagnostic report. Component: MATLAB Function | Category: Coder error

Please help me to solve this problem.

Answer 1

[Sebastian Castro]

If you won't be generating code from your Simulink model (i.e., you just want a desktop simulation), you could do a few things:

1. Place your entire code in a regular MATLAB function .m file, and call it from Simulink using an Interpreted MATLAB Function block instead.
2. Place just the unsupported piece (the generation of the function handle) in a separate function and call it as interpreted using coder.extrinsic.

... or, my favorite approach:

3. Given that you seem to be modeling some kind of first-order set of equations, it would probably be MUCH easier (and numerically accurate) to implement the equations in Simulink with Integrator blocks!

http://blogs.mathworks.com/seth/2008/05/23/how-to-draw-odes-in-simulink/

- Sebastian

[Muhammad Zeeshan Babar]

Thankyou Sebastian. But the theme of writing the model in this form (as I mentioned in my question) is that I am using these function handle in other MATLAB function as well. e.g

r=0.1; s=[0,1]; z = h(s) + r*randn; s=f(s)+r*randn;

you can see that I am evaluating h and f here on some values of s. It is running in a loop where I called the estimation algorithm. That's why I need to use this interpretation. I am trying to make multiple MATLAB function blocks in order to solve a parameter estimation problem. This is only a portion of my problem where I just need my model to simulate and give me f and h as output. It is working in .m file but not in Simulink.

[Vignesh Ramakrishnan]

@Sebastian Castro, quick follow-up on this question: Say I have solved a first order ODE in Simulink and called the simulink file say ode.slx, using:

y=sim("ode.slx");

I wish to make a function handle for this call, and hopefully make a phase portrait with a quiver plot and contour lines. Is there some way to pull that off?