Pure Riccati solvers


If I do not make mistake, there are no pure Riccati solvers (that is, hpipm_ocp_qp) for the nonlinear optimal control problems.
It seems that hpipm_ocp_qp is available for solving QP but is not for the QP subproblem of SQP.
Do you have a plan to implement such methods?

Thank you very much,
Sotaro Katayama


actually HPIPM_OCP_QP is the default QP solver within the SQP method in acados.
It is for example used here.

Hi FreyJo,

Thank you for replying!
I thought that the partial condensing routine, hpipm_d_part_cond, is used in PARTIAL_CONDENSING_HPIPM option.
But actually, hpipm_d_ocp_qp is used within the option.
Is my understanding correct?

Sotaro Katayama


you are right.
But it depends on the partial condensing horizon qp_solver_cond_N (QP solver: New horizon after partial condensing. Set to N by default → no condensing., see Python API — acados documentation)

So if you don’t set qp_solver_cond_N partial condensing is basically doing nothing and solving the QP using hpipm_d_ocp_qp.