MATLAB Answers

0

Infinite while loop in Matlab function block

Asked by Matthieu GATINE on 5 Oct 2018
Latest activity Answered by Walter Roberson
on 8 Oct 2018
I have made this programm to implemente it in a Matlab function block in Simulink :
function Open_area1 = fcn(Moisture_Sensor_area_1_OUT,Moisture_instruction_min,Moisture_instruction_max)
Open_area1 = 0;
if (Moisture_Sensor_area_1_OUT<Moisture_instruction_min)
while(Moisture_Sensor_area_1_OUT<Moisture_instruction_max)
Open_area1 = 1;
end
end
end
But the while loop make an infinite simulation time.

  2 Comments

That means the following condition is always true
Moisture_Sensor_area_1_OUT<Moisture_instruction_max
Do same sort of modification (update), so that it not true after some required iteration
How can I update the value of Moisture_Sensor_area_1 when the function block is in the loop ? Does the simulation is stop during the execution of the function block ?
The input signal is a sampled sinus.

Sign in to comment.

Products


Release

R2018a

2 Answers

Answer by Walter Roberson
on 8 Oct 2018
 Accepted Answer

Output = double(Input >= Min & Input <= Max) ;
No loop. No if. But you do need to substitute appropriate variables.

  0 Comments

Sign in to comment.


Answer by TAB
on 8 Oct 2018

I guess, you are trying to run the loop for checking Moisture_Sensor_area_1_OUT<Moisture_instruction_min condition for every sample time.
But Simulink's Matlab Function runs in different way. It is invoked at every sample time during model execution.
At t=0, Get the 3 function inputs from previous blocks, Call fcn with inputs, collect fcn output and send to next block
At t=1, Get the 3 function inputs from previous blocks, Call fcn with inputs, collect fcn output and send to next block
At t=2, Get the 3 function inputs from previous blocks, Call fcn with inputs, collect fcn output and send to next block
...
... and so on.
Inputs to fcn remains same during the a sample time, so loop will always run into infinity.
You don't need to use while loop. You can just use if condition to set output.

  0 Comments

Sign in to comment.