fix python example

Author: lvanroye

examples/ocp_impl_example_opti.py

@@ -41,6 +41,7 @@ def path_constraints(uk, xk ,k):
 opti = cs.Opti()
 x = []
 u = []
+ng = []
 for k in range(K):
     x.append(opti.variable(nx[k]))
     u.append(opti.variable(nu[k]))
@@ -51,6 +52,7 @@ def path_constraints(uk, xk ,k):
     path_constr = path_constraints(u[k], x[k], k)
     for constr in path_constr:
         opti.subject_to(constr)
+    ng.append(cs.vvcat(path_constr).nnz())
 # set the objective
 J = 0
 for k in range(K):
@@ -60,4 +62,4 @@ def path_constraints(uk, xk ,k):
 opti.solver('fatrop', {'structure_detection':'manual', 'nx': nx, 'nu':nu, 'ng':ng, 'N':K-1, "expand": True, "fatrop.mu_init":1e-1, "jit":False, "jit_options": {"flags": "-O3", "verbose": True}})
 opti.to_function("opti_func", [], [opti.x]).generate('casadi_generated.c', {"with_header": True})
 # opti.solver('ipopt', {'ipopt.print_info_string': 'yes', 'ipopt.kappa_d':0.})
-opti.solve()
+opti.solve()