Subscripting into an mxArray is not supported for code generation - I think it's the colon that's the issue

This part of my code

    V = zeros(n,m+1);
    V(:,1) = (1/beta)*w;

is giving me an error "Subscripting into an mxArray is not supported for code generation", when I use MATLAB Coder to create a Mex file. But if I can't fill V that way and so forth what is the correct way to do it? Other places I get "Unexpected MATLAB operator" and the MATLAB Coder points me to the ":"

Answer 1

[James Tursa]

What happens if you use explicit indexes?

V(1:n,1) = (1/beta)*w;

[Mads]

Apparently, it is not the issue after all. I did a test earlier in the code:

test= rand(5,1);
test2 = zeros(5,2);
test2(:,1) = test;
test2(1:5,2) = 2*test;

and it passes, so basically, the original error is misleading. So there is a main function and a subfunction. And things start to go wrong from the point where I call the subfunction in which the original error was, although, I conduct the same test in the subfunction and it passes. So I'm left without a clue. I worry there is one error leading to other errors...

[Mads]

I finally managed to locate the seeding error of all other errors. I'm disappointed by the fact that I was not allowed to use spdiags() even though I made it extrinsic ("coder.extrinsic('spdiags')"). This has resulted in a workaround that finally has made the MEX slower than the native matlab script because I at some point am forced to use non-sparse matrices...