Is it better to use switch block or if-else block in Simulink?

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Pallanti Srinivasa Rao 2017-11-12

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评论： Birdman 2017-11-12

Hi,

I have the following set of code in Matlab. I want to know, which is the best way to implement this code in Simulink (using switch block or if-else block!?).

If a > 0 c = m + n; else c = m - n; end

Thanks

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Answer 1

Birdman 2017-11-12

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Well, in this kind of situations, it is better to use MATLAB Function block in Simulink since in case of code generation, MATLAB Functions are compatible for C code generation and several functions used in command line also become usable in Simulink by the help of MATLAB Functions. See the links below:

https://www.mathworks.com/help/simulink/slref/matlabfunction.html https://www.mathworks.com/help/simulink/ug/functions-supported-for-code-generation-alphabetical-list.html

Also, you may write a function for your algorithm as follows:

function c=SWITCH(a,m,n)
c=0;%initializing
   if(a>0)
   c=m+n;
   else
   c=m-n;
   end
end

where you have three inputs and one output. Hope this helps.

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Birdman 2017-11-12

Oh, I thought m and n are variables. If they are functions, then the situation will be different. I thought there is a 3 input-1 output function and you try to implement it. Now, I do not know if this is an answer for your question, but I read this sentence from the help documentation of Simulink Function:

You can call a Simulink Function block from a Function Caller block, a MATLAB Function block, or a Stateflow® Chart.

After reading this, what comes to my mind is this:

You calculate your functions m and n in your already defined Simulink Function blocks. Then, take those 2 outputs respectively from those blocks and give them as inputs to your MATLAB Function blocks. Meanwhile, you call m and n functions from your MATLAB Function block. Your third input will still be your condition, which is denoted by a. Then you make the calculations. Hope you understand what I mean. I suggest you not to use switch block in case of code generation. But if you find using switch block more useful for simulation purposes only, you may also use it.

Pallanti Srinivasa Rao 2017-11-12

Thank you so much. And thanks for the valuable inputs on code generation too.

Birdman 2017-11-12

You are welcome. If my answer solves the issue, then accept the answer so that other people having the same problem will know there is a working solution.

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