Hi all,

Recenlty, I’ve been switching between the MinGW and MSVC compilers (Windows, Matlab interface), and I noticed different runtime behaviour between the two. With MinGW, I get a solution for my simple model, as expected. However, when I (only) change the compiler to MSVC, I run into a QP solver failure (ACADOS_QP_FAILURE). Playing around with the qp solver settings (I’m using hpipm) sometimes makes the error dissapear, so I’m guessing that HPIPM and MSVC don’t play nice together. @giaf is this something you recognize?

Below, I pasted a minimal example of the Matlab code that yields errors with MSVC, but not with MinGW.

Thank you for any insights that might solve this issue.

```
function minimal_example()
clear all
N_ocp = 10; % control horizon (steps)
Ts = 0.01; % timestep/sampling time
T_ocp = Ts*N_ocp; % control horizon (time)
%%%%%%%%%%%%%%%%%%%%%%%
%%%%%% OCP MODEL %%%%%%
%%%%%%%%%%%%%%%%%%%%%%%
ocp_model = acados_ocp_model();
ocp_model.set('name', 'example');
ocp_model.set('T',T_ocp);
%%%%%% state %%%%%
X = casadi.SX.sym('X');
V = casadi.SX.sym('V');
F = casadi.SX.sym('F');
sym_x = vertcat(X, V, F);
ocp_model.set('sym_x', sym_x);
ocp_model.set('sym_xdot', casadi.SX.sym('xdot', 3, 1));
%%%%%% inputs %%%%%
dF = casadi.SX.sym('dF');
sym_u = [dF];
ocp_model.set('sym_u', sym_u);
%%%%%% model %%%%%
m = 1;
A = [0, 1, 0;
0, 0, 1/m;
0, 0, 0];
B = [0;
0;
1];
ocp_model.set('dyn_expr_f', A * sym_x + B * sym_u);
ocp_model.set('dyn_type', 'explicit');
%%%%%% constraints %%%%%
dF_u = 1; dF_l = -dF_u;
ocp_model.set('constr_Jbu', 1);
ocp_model.set('constr_lbu', dF_l);
ocp_model.set('constr_ubu', dF_u);
%%%%%% cost %%%%%
W_X = 1e1; W_V = 1e-6; W_F = 1e2; W_dF = 1e-6;
ocp_model.set('cost_type', 'linear_ls');
ocp_model.set('cost_type_e', 'linear_ls');
ocp_model.set('cost_Vx', [1, 0, 0;
0, 1, 0;
0, 0, 1;
0, 0, 0]);
ocp_model.set('cost_Vu', [0;
0;
0;
1]);
ocp_model.set('cost_Vx_e', [1, 0, 0;
0, 1, 0;
0, 0, 1]);
ocp_model.set('cost_W', [W_X, 0, 0, 0;
0, W_V, 0, 0;
0, 0, W_F, 0;
0, 0, 0, W_dF]);
ocp_model.set('cost_W_e', [W_X, 0, 0;
0, W_V, 0;
0, 0, W_F]);
%%% trajectory %%%
ocp_model.set('constr_x0', [0;0;0]);
ocp_model.set('cost_y_ref', [1;0;0;0]);
ocp_model.set('cost_y_ref_e', [1;0;0]);
%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%% OCP OPTIONS %%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%
% ocp options
ocp_opts = acados_ocp_opts();
ocp_opts.set('qp_solver','partial_condensing_hpipm'); % --> options that don't play nice with MSVC compiler
ocp_opts.set('qp_solver_cond_N', 5); % --> options that don't play nice with MSVC compiler
% ocp_opts.set('qp_solver_iter_max', 10); % --> options that don't play nice with MSVC compiler
ocp_opts.set('regularize_method', 'no_regularize');
ocp_opts.set('sim_method', 'erk');
%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%% OCP SOLVER %%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%
% create ocp solver
ocp = acados_ocp(ocp_model, ocp_opts);
% solve OCP
ocp.solve();
x_traj = ocp.get('x');
% print stats
ocp.print('stat');
status = ocp.get('status');
fprintf('OCP finished with code %.f: %s\n\n', status, status_code(status+1));
%%%%%%%%%%%%%%%%%%
%%%%%% PLOT %%%%%%
%%%%%%%%%%%%%%%%%%
figure
states = {'X', 'V', 'F'};
ylabels = {{'Position [m]'}, {'Velocity [m/s]'}, {'Force [N]'}};
for i=1:length(states)
subplot(length(states), 1, i);
hold on
plot((0:N_ocp)*Ts, x_traj(i,:));
grid on;
xlim([0 T_ocp]);
ylabel(ylabels{i})
legend(states{i},'Location','southeast');
end
end % function
function msg = status_code(code)
msgs = [ ...
"ACADOS_SUCCESS", ... % success
"ACADOS_FAILURE", ... % failure
"ACADOS_MAXITER", ... % maximum number of iterations reached
"ACADOS_MINSTEP", ... % minimum step size in QP solver reached
"ACADOS_QP_FAILURE", ... % qp solver failed
"ACADOS_READY"
];
msg = msgs(code);
end % function
```