linspace not working on MATLAB Coder

I have some problem with linspace operator inside simulink.

I want to take a decision among a finite set of angles, which I define as

delta = linspace(-r_max*Tc_usbl,r_max*Tc_usbl,decisions)

r_max being the maximum angular velocity, Tc_usbl the control period, 'decisions' the number of angles I want in my set. In the Command Window everything works fine; and iy should work in Simulink too, since I succesfully tried

function fcn()
    delta_max = -0.1; decisions = 3;
    for delta = linspace(-delta_max,delta_max,decisions)
        delta
    end

But my code actually is

function fcn(r_max,Tc_usbl,decisions)
    for delta = linspace(-r_max*Tc_usbl,r_max*Tc_usbl,decisions)
        delta
    end

Where all arguments are static parameters from the Workspace.

I get the following error:

    FOR loop index expressions of unknown size are only supported if they are of the form A:B or A:B:C

If it is not possible to use linspace the way I'd like to, does someone has any other idea? But how can I get with colon something similar to

linspace(-pi/4,pi/4,2)

Answer 1

[Stephen23]

In MATLAB it is usually better to loop over indices. Perhaps this would work:

V = linspace(-r_max*Tc_usbl,r_max*Tc_usbl,decisions);
for k = 1:numel(V)
    delta = V(k)
    ... do whatever with delta
end

[Matteo Paiano]

I really appreciate that! Such an elegant and simple solution! How silly of me