Hi acados Team 
unfortunately I am having issues with constraints when creating a Simulink sfunction. What I tried to do is to set up a constraint like this:
ocp_model.set('constr_type', 'auto');
ocp_model.set('constr_expr_h',vertcat(0.5*x(1)+0.5*x(2),u))
When creating the ocp_solver this constraint is reformulated into a linear constraint and a bound for u. The reformulation looks correct. (By the way, this is a very cool feature! 
) Then, when I try to create an sfunction, I encounter an error.
The error can be easily reproduced with the getting_started\minimal_example_ocp.m. Just change the code in line 87 from
ocp_model.set('constr_expr_h', model.expr_h);
to this
ocp_model.set('constr_expr_h', model.sym_x(1)+model.sym_x(2));
and run getting_started\simulink_example.m. In my case I get the following error message:
Error using acados_template_mex.render_acados_templates>render_file (line 246)
rendering acados_solver.in.c failed.
command: D:\acados\examples\acados_matlab_octave\..\..\bin\t_renderer.exe
"D:\acados\examples\acados_matlab_octave\..\..\interfaces\acados_template\acados_template\c_templates_tera\*"
"acados_solver.in.c" "D:\acados\examples\acados_matlab_octave\getting_started\acados_ocp_nlp.json"
"acados_solver_pendulum.c"
returned status 1, got result:
Error: Failed to render 'acados_solver.in.c'
Reason: Variable `constraints.D[j][k]` not found in context while rendering 'acados_solver.in.c': the
evaluated version was `constraints.D.0.0`. Maybe the index is out of bounds?
Some additional Info:
- I am using the acados version as of the 19th of March. Older versions of acados are also effected, I tried this with a version from November of last year.
- Using
set('constr_type','bgh')and directly settingconstr_Candconstr_Dbrings up the same error message.
Can you tell from my description if I should formulate the constraint in another way or if this is a bug related to the process of creating an sfunction?
Thanks a lot for your help! 
Christian
