It is not possible to define an output (‘y1[]’) with undefined or variable dimension in the ‘OutputFcnSpec’ when using ‘legacy_code’ with 'sfcn_cmex_generate'. Unlike inputs, output dimensions must be explicitly defined in the function signature (e.g., ‘y1[10]’), because Simulink requires fixed output dimensions for S-Functions at compile time.
You can try the following workarounds:
1. You can use manual modification after code generation (as you mentioned).
2. You can use “mdlInitializeSizes” in a hand-written wrapper ‘S-Function’ to set output dimensions dynamically but this is not automated via ‘legacy_code’.
You can refer to the following documentation of “mdInitializeSizes” for a better understanding: https://in.mathworks.com/help/simulink/sfg/mdlinitializesizes.html
Hope this helps!
