MATLAB: Dynamically sized outputs / work vectors using the Legacy Code Tool

Question

Hello everyone,

I am trying to build an s – function using the Legacy Code Tool and I have the following problem:

I work with matrices and I want some of the outputs and work vectors to have a dynamically sized first dimension and a second dimension whose size depends on a parameter or input.

So, I want to do this one: (dynamically sized input u1, parameter p1)

def.OutputFcnSpec = 'void step2(double y1[size(u1,1)][size(u1,2)], double u1[][], int32 p1, int32 size(u1,1), int32 size(u1,2), double work1[size(u1,1)][p1], double y2[size(u1,1)][p1])';

But, the compiler does not allow that and I get the following error: "When specifying input/output/parameter/work dynamically sized, all dimensions must be dynamically sized (dwork 1)"

Does anyone have an idea of how I could do that?

Thank you very much in advance.

Agamemnon

Answer 1

What you're looking to do is output a variable-size signal. Unfortunately, I don't think the Legacy Code Tool can handle generation of S-functions that produce variable-size signals. Perhaps you could generate the S-function for a fixed-signal signal first and then modify it manually to support variable-size signals. See here for an example of an S-function that supports this feature.