Simulink HDL code generation for custom matlab functions

Hello,

I am trying to generate HDL code for a custom Matlab function I have in Simulink. I am just trying to learn how things work basically so my "custom" function block is very simple;

function y = my_function(u, k)
  y = atan2(u, k);
end

However, when I try to generate an HDL code for this function I get the following error, "Block 'test/Subsystem/MATLAB Function' is unsupported for HDL code generation when in native floating-point mode". When I just use atan2 block from Simulink I can generate HDL code perfectly fine but when I try my own custom function block I get this error. Simulink simulation works though, I get proper outputs from my scopes.

How can I fix this? Do I have to use separate floating point libraries or am I missing something else?

Thanks in advance.