Solve method: OptInterface class

Syntax

Solve(modelID, SolutionType [, &objValue [, name-value_pairs]])

Where name-value_pairs is a list of solver setting parameter values in the form: 

[parmname1, parmvalue1 [, parmname2, parmvalue2]]...

Description

The Solve method solves the specified model using the currently active solver settings, and provides an objective value as the solution output. You can override the solver setting parameters. The returned solution status is a predefined system constant.

Parameters

Parameter Description

ModelID

Specify as a string the name of the optimization model you want to solve. This is the name used for the model definition in Application Designer.

SolutionType

Specify a system constant indicating the type of solution detail you want the model to be solved for.

  • %OPT_DUAL: Generate dual value attributes.

  • %OPT_SLACK: Generate slack value attributes.

  • %OPT_RCOST: Generate reduced cost attributes.

You can also combine any or all of these system constants, by connecting them with a plus sign (+), for example: %OPT_DUAL + %OPT_RCOST.

&objValue

Specify a reference to a variable of type float. This variable contains the output objective value produced by the solver upon successfully solving the specified optimization model.

parmname and parmvalue

Specify a solver setting parameter ID and value to override the original value you specified for the solver setting in the analytic type definition. You can override any or all of the solver setting parameter values.

See Optimization Framework: Configuring Models for Optimization.

Returns

One of the following system constants:

%OptInter_Fail: The solver fails to solve the problem.

%Opt_Optimal: The solution is optimal.

%Opt_Infeasible: The solution is infeasible.

%Opt_Unbounded: The solution is unbounded.

%Opt_Timeup: The solver reached the time limit specified in the solver setting.

%Opt_Iterlimit: The solver reached the limit on the number of iterations specified in the solver setting.

%Opt_LP_Max_Sols: The solver generated maximum number of solutions without improvement.

%Opt_Idle: The solution shows no improvement in a specified time limit.

%Opt_Unknown: The solver status is unknown.

%Opt_MIP_NumSolutions: The specified number of solutions corresponding to an MIP solver reached.

%Opt_MIP_NumNodes: The specified number of nodes corresponding to an MIP solver reached.

%Opt_Aborted: The solver aborted.

%Opt_User_Exit: A user exit was encountered.

%Opt_First_LP_NoOpt: While solving an MIP, the first LP solution obtained was not optimal.

Example

Following is an example of the basic use of the Solve method:

Local OptInterface &oi = CreateOptInterface();

Local float &objval = 0.0;
Local integer &result;
Local string &modelId = "QE_PSA_MODEL";
Local string &varArrayName = "X";   
Local integer &solType;

&solType = %Opt_RCost + %Opt_Dual + %Opt_Slack;

/* Solve the problem */
&result = &oi.Solve("QE_PSA_MODEL", &solType, &objval);

If & result = %Opt_Optimal Then
   &oi.DumpMsgToLog(%Severity_Warn, " Solution Status =  " Optimal !!!");
Else
   &oi.DumpMsgToLog(%Severity_Warn, " Solution Status =  " | &result );
End-If;

Following is an example of a solver setting parameter override:

Local OptInterface &oi = CreateOptInterface();
Local float &objval = 0.0;
Local integer &result;

/* This overrides the solver setting for MPS_Filename and generates
 an MPS file called myfile.mps instead of the name specified
 in the current solver setting parameter. */

&result = &oi.Solve("QE_PSA_MODEL", %Opt_Primal, &objval, "MPS_FileName",
 "myfile");