lmm::Constraint* L1 = Sys.constraint_new(nullptr, a);
lmm::Constraint* L2 = Sys.constraint_new(nullptr, b);
lmm::Constraint* L3 = Sys.constraint_new(nullptr, a);
lmm::Constraint* L1 = Sys.constraint_new(nullptr, a);
lmm::Constraint* L2 = Sys.constraint_new(nullptr, b);
lmm::Constraint* L3 = Sys.constraint_new(nullptr, a);