Attributes

To query and modify properties of a COPT model is through the attribute interface. A variety of different attributes are available, and they can be associated with solutions, or the model.

Problem related

Problem related attributes provide the relevant information of the model composition and description. The names and descriptions of these attributes are summarized below.

Table 14 Problem related attributes

Name	Type	Description
Cols	Integer	Number of variables (columns) in the problem
PSDCols	Integer	Number of PSD variables in the problem
Rows	Integer	Number of constraints (rows) in the problem
Elems	Integer	Number of non-zero elements in the coefficient matrix
QElems	Integer	Number of non-zero quadratic elements in the quadratic objective function
PSDElems	Integer	Number of PSD terms in objective function
SymMats	Integer	Number of symmetric matrices in the problem
Bins	Integer	Number of binary variables
Ints	Integer	Number of integer variables
Soss	Integer	Number of SOS constraints
Cones	Integer	Number of Second-Order-Cone constraints
ExpCones	Integer	Number of exponential cone constraints
AffineCones	Integer	Number of affine cone constraints
QConstrs	Integer	Number of quadratic constraints
PSDConstrs	Integer	Number of PSD constraints
LMIConstrs	Integer	Number of LMI (Linear Matrix Inequalities) constraints
Indicators	Integer	Number of indicator constraints
MultiObjs	Integer	Number of objectives in a multi-objective model
ObjSense	Integer	The optimization direction
ObjConst	Double	The constant part of the objective function
HasQObj	Integer	Whether the problem has quadratic objective function
HasPSDObj	Integer	Whether the problem has PSD terms in objective function
HasNLObj	Integer	Whether the problem has nonlinear terms in objective function
IsMIP	Integer	Whether the problem is a MIP

• Cols

  Integer attribute.

  Number of variables (columns) in the problem.

• PSDCols

  Integer attribute.

  Number of PSD variables in the problem.

• Rows

  Integer attribute.

  Number of constraints (rows) in the problem.

• Elems

  Integer attribute.

  Number of non-zero elements in the coefficient matrix.

• QElems

  Integer attribute.

  Number of non-zero quadratic elements in the quadratic objective function.

• PSDElems

  Integer attribute.

  Number of PSD terms in objective function.

• SymMats

  Integer attribute.

  Number of symmetric matrices in the problem.

• Bins

  Integer attribute.

  Number of binary variables.

• Ints

  Integer attribute.

  Number of integer variables.

• Soss

  Integer attribute.

  Number of SOS constraints.

• Cones

  Integer attribute.

  Number of Second-Order-Cone constraints.

• ExpCones

  Integer attribute.

  Number of exponential cone constraints.

• AffineCones

  Integer attribute.

  Number of affine cone constraints.

• QConstrs

  Integer attribute.

  Number of quadratic constraints.

• PSDConstrs

  Integer attribute.

  Number of PSD constraints.

• LMIConstrs

  Integer attribute.

  Number of LMI (Linear Matrix Inequalities) constraints.

• Indicators

  Integer attribute.

  Number of indicator constraints.

• MultiObjs

  Integer attribute.

  Number of objectives in a multi-objective model.

• ObjSense

  Integer attribute.

  The optimization direction.

• ObjConst

  Double attribute.

  The constant part of the objective function.

• HasQObj

  Integer attribute.

  Whether the problem has quadratic objective function.

• HasPSDObj

  Integer attribute.

  Whether the problem has PSD terms in objective function.

• HasNLObj

  Integer attribute.

  Whether the problem has nonlinear terms in objective function.

• IsMIP

  Integer attribute.

  Whether the problem is a MIP.

Solution related

Solution related attributes provide the relevant information of the solution composition and description. The names and descriptions of these attributes are summarized below.

Table 15 Solution related attributes

Name	Type	Description
Status	Integer	Optimization status
LpStatus	Integer	The LP status
MipStatus	Integer	The MIP status
SimplexIter	Integer	Number of simplex iterations performed
BarrierIter	Integer	Number of barrier iterations performed
NodeCnt	Integer	Number of explored nodes
PoolSols	Integer	Number of solutions in solution pool
TuneResults	Integer	Number of parameter tuning results
HasSol	Integer	Whether a solution is available
HasLpSol	Integer	Whether LP solution is available
HasMipSol	Integer	Whether MIP solution is available
HasBasis	Integer	Whether LP basis is available
HasDualFarkas	Integer	Whether the dual Farkas of an infeasible LP problem is available
HasPrimalRay	Integer	Whether the primal ray of an unbounded LP problem is available
IISCols	Integer	Number of bounds of columns in IIS
IISRows	Integer	Number of rows in IIS
IISSOSs	Integer	Number of SOS constraints in IIS
IISIndicators	Integer	Number of indicator constraints in IIS
HasIIS	Integer	Whether IIS is available
HasFeasRelaxSol	Integer	Whether feasibility LP-relaxation solution is available
IsMinIIS	Integer	Whether the computed IIS is minimal
FeasRelaxObj	Double	Feasibility relaxation objective value
HasSensitivity	Integer	Whether sensitivity analysis results are available for LP problem
ObjVal	Double	Optimal objective value
ObjBound	Double	Current best bound on the optimal objective value
LpObjval	Double	Optimal objective value for continuous convex optimization problem
BestObj	Double	Current best objective value for MIP
BestBnd	Double	Current best bound for MIP
BestGap	Double	Current best relative gap for MIP
SolvingTime	Double	The time spent for the optimization (in seconds)

• Status

  Integer attribute.

  Optimization status.

  Please refer to General Constants: Solution status for possible values.

• LpStatus

  Integer attribute.

  The LP status.

• MipStatus

  Integer attribute.

  The MIP status.

• SimplexIter

  Integer attribute.

  Number of simplex iterations performed.

• BarrierIter

  Integer attribute.

  Number of barrier iterations performed.

• NodeCnt

  Integer attribute.

  Number of explored nodes.

• PoolSols

  Integer attribute.

  Number of solutions in solution pool.

• TuneResults

  Integer attribute.

  Number of parameter tuning results.

• HasSol

  Integer attribute.

  Whether a solution is available.

• HasLpSol

  Integer attribute.

  Whether LP solution is available.

• HasMipSol

  Integer attribute.

  Whether MIP solution is available.

• HasBasis

  Integer attribute.

  Whether LP basis is available.

• HasDualFarkas

  Integer attribute.

  Whether the dual Farkas of an infeasible LP problem is available.

• HasPrimalRay

  Integer attribute.

  Whether the primal ray of an unbounded LP problem is available.

• IISCols

  Integer attribute.

  Number of bounds of columns in IIS.

• IISRows

  Integer attribute.

  Number of rows in IIS.

• IISSOSs

  Integer attribute.

  Number of SOS constraints in IIS.

• IISIndicators

  Integer attribute.

  Number of indicator constraints in IIS.

• HasIIS

  Integer attribute.

  Whether IIS is available.

• HasFeasRelaxSol

  Integer attribute.

  Whether feasibility LP-relaxation solution is available.

• IsMinIIS

  Integer attribute.

  Whether the computed IIS is minimal.

• FeasRelaxObj

  Double attribute.

  Feasibility relaxation objective value.

• HasSensitivity

  Integer attribute.

  Whether sensitivity analysis results are available for LP problem.

• ObjVal

  Double attribute.

  Optimal objective value.

• LpObjval

  Double attribute.

  Optimal objective value for continuous convex optimization problem.

• ObjBound

  Double attribute.

  Current best bound on the optimal objective value.

• BestObj

  Double attribute.

  Current best objective value for MIP.

• BestBnd

  Double attribute.

  Current best bound for MIP.

• BestGap

  Double attribute.

  Current best relative gap for MIP.

• SolvingTime

  Double attribute.

  The time spent for the optimization (in seconds).

Note

The attributes LpStatus, MipStatus, HasLpSol, HasMipSol, LpObjval, BestObj and BestBnd are deprecated. It is recommended to use Status, HasSol, ObjVal and ObjBound instead, as they provide a unified interface for querying the solution status, whether a solution is available, and optimal objective value across all supported problem types, including linear programming, integer programming, and convex/non-convex optimization problems.

Methods for accessing attributes

In different programming interfaces, the ways to access attributes are slightly different. For details, please refer to the corresponding chapters for each programming language API:

• C API: C API Functions: Accessing attributes

• C++ API: C++ API Reference: Attributes

• C# API: C# API Reference: Attributes

• Java API: Java API Reference: Attributes

• Python API: Python API Reference: Attributes