Knitro attributes

Knitro exposes a set of read-only attributes that can be queried after a solve to inspect model properties and solution statistics. See Querying attributes programmatically for how to query attributes in each interface.

Model

Name	API constant	ID	Type	Description
numvars	KN_ATTR_NUM_VARS	100	integer	Number of variables in the model.
numcons	KN_ATTR_NUM_CONS	101	integer	Number of constraints in the model.
numcompcons	KN_ATTR_NUM_COMPCONS	102	integer	Number of complementarity constraints in the model.
numrsds	KN_ATTR_NUM_RSDS	103	integer	Number of residuals in the model (for least-squares problems).
objgoal	KN_ATTR_OBJ_GOAL	110	integer	Objective goal: 0 for minimize, 1 for maximize.
objtype	KN_ATTR_OBJ_TYPE	111	integer	Type of objective function: -1 for constant, 0 for general, 1 for linear, 2 for quadratic.
objgradnnz	KN_ATTR_OBJ_GRAD_NNZ	200	long integer	Number of nonzeros in the objective gradient.
jacnnz	KN_ATTR_JAC_NNZ	201	long integer	Number of nonzeros in the constraint Jacobian.
hessnnz	KN_ATTR_HESS_NNZ	202	long integer	Number of nonzeros in the Hessian of the Lagrangian.

General

Name	API constant	ID	Type	Description
numiters	KN_ATTR_NUM_ITERS	120	integer	Number of iterations performed by the solver for continuous solves.
numcgiters	KN_ATTR_NUM_CG_ITERS	121	integer	Number of conjugate gradient iterations performed.
numfcevals	KN_ATTR_NUM_FC_EVALS	122	integer	Number of function/constraint evaluations.
numgaevals	KN_ATTR_NUM_GA_EVALS	123	integer	Number of gradient evaluations.
numhevals	KN_ATTR_NUM_H_EVALS	124	integer	Number of Hessian evaluations.
numhvevals	KN_ATTR_NUM_HV_EVALS	125	integer	Number of Hessian-vector product evaluations.
objvalue	KN_ATTR_OBJ_VALUE	300	double	Final objective function value.
absfeaserror	KN_ATTR_ABS_FEAS_ERROR	301	double	Absolute feasibility error at the solution.
relfeaserror	KN_ATTR_REL_FEAS_ERROR	302	double	Relative feasibility error at the solution.
absopterror	KN_ATTR_ABS_OPT_ERROR	303	double	Absolute optimality error at the solution.
relopterror	KN_ATTR_REL_OPT_ERROR	304	double	Relative optimality error at the solution.
solvetimecpu	KN_ATTR_SOLVE_TIME_CPU	310	double	CPU time spent in the solve (in seconds).
solvetimereal	KN_ATTR_SOLVE_TIME_REAL	311	double	Real/wall-clock time spent in the solve (in seconds).

MIP

Name	API constant	ID	Type	Description
mipnumnodes	KN_ATTR_MIP_NUM_NODES	140	integer	Number of nodes explored in the MIP branch-and-bound tree.
mipnumsolves	KN_ATTR_MIP_NUM_SOLVES	141	integer	Number of subproblem solves in the MIP algorithm.
mipabsgap	KN_ATTR_MIP_ABS_GAP	340	double	Absolute gap between incumbent and relaxation bound in MIP.
miprelgap	KN_ATTR_MIP_REL_GAP	341	double	Relative gap between incumbent and relaxation bound in MIP.
mipincumbentobj	KN_ATTR_MIP_INCUMBENT_OBJ	342	double	Objective value of the current best integer solution in MIP.
miprelaxationbnd	KN_ATTR_MIP_RELAXATION_BND	343	double	Best relaxation bound in MIP.