Infinite loop in Matlab Fctn Block

Why did I run into infinite loop (see coode below)? Also, I tried to stop the simulation by clicking on the stop button on the model window but it didn' work. i is the input from a ramp function in Simulink model. Thanks

function [y1,y2] = UPC(i) %#codegen persistent ii ii=0; if isempty(ii) y1=ii; y2=ii; else y1=i; y2=i; end while (i<5) y1=i+1; y2=i-1; end_ *_ *

Answer 1

[Niklas Nylén]

The condition to exit the while loop is that i>=5 and you never change the value of i in the loop, which means you will never exit the loop if the input value of i is less than 5.

For every time step in your model the code in an embedded matlab code block will run from the first line of code to the last. What it looks like is that you want to perform the operation inside the while loop if i<5, not while i<5.

[William]

Why is i not changing? i is the input from a ramp function (slope 1). Shouldn't i be increase as simulation time increase?

[Niklas Nylén]

No, since all the code in the embedded code block will run on every iteration of the model. What I'm guessing you would like to do is something like this:

 function [y1,y2] = UPC(i) 
%#codegen 
if i<5 
    y1=i+1; 
    y2=i-1;
else
    y1=i;
    y2=i; 
end

The code above will run once for every time step of the simulink model. You do not need to add a loop inside the code to keep it running with the model.