Can an S-Function builder input be symbolic?

I'm using S-Function builder in R2021a, and I'd like to set the input size to a symbolic dimension. Is this possible?

Answer 1

[MathWorks Support Team]

S-Function Builder in R2021a does not currently support symbolic dimensions.

If you want to continue down the route of using S-Functions, you will have to modify the generated S-Function to use symbolic dimensions. This doc page is a good starting point:

https://www.mathworks.com/help/ecoder/ug/configure-dimension-variants-for-simulink-function-s-function-blocks.html

If you are open to alternatives to the S-Function approach, try the C Function block. The C Function block supports Symbolic Dimensions without doing any extra work, and it lets you specify Initialize, Start, Output, and Terminate code.

Here is relevant documentation about this:

https://www.mathworks.com/help/simulink/slref/cfunction.html