Procedure GMP::Instance::GetInfeasibleData(GMP, parSet, message, method, effort, textFormat)

GMP::Instance::GetInfeasibleData

NOTE: THIS PROCEDURE IS NOT AVAILABLE (YET) IN ANY OFFICIAL AIMMS RELEASE.

Usually, methods for detecting the cause of an infeasibiliy in a mathematical model return information about constraints and variables. The procedure GMP::Instance::GetInfeasibleData uses a different approach, namely, it can be used to retrieve information about parameters that cause a (linear) mathematical program to become infeasible.

This procedure only considers parameters without a definition, i.e., parameters that can be changed by, e.g., an end user.

This procedure returns information in two ways. First, it will fill the output message argument with a text describing the cause of the infeasibility. Second, it will fill the suffix .SuspicionLevel for each parameter that contributes to the infeasibility.

GMP::Instance::GetInfeasibleData(
     GMP,            ! (input) a generated mathematical program
     parSet,         ! (input) a set of parameters
     message,        ! (output) a string parameter
     [method],       ! (optional) a scalar integer value
     [effort],       ! (optional) a scalar integer value
     [textFormat]    ! (optional) a scalar binary value
     )

Arguments

GMP

An element in AllGeneratedMathematicalPrograms.

parSet

A subset of AllParameters.

message

A string that describes the cause of the infeasibility.

method

An integer scalar value between 0 and 4 that specifies the method used to find the cause of the infeasibility. Default is 0. The methods are described below.

effort

An integer scalar value between 0 and 2 that specifies the effort level used by this procedure to find the cause of the infeasibility. Default is 2. A higher value means more effort.

textFormat

A scalar binary value to indicate whether the message should use plain text (value 0; the default) or HTML formatting (value 1).

Return Value

The procedure returns 1 on success, or 0 otherwise.

Note

• The GMP must be linear.

• Typically, AllParameters is passed for the parSet argument.

• The procedure GMP::Instance::GetInfeasibleData will use one of the following methods, as specified by the method argument:

  • 0: IIS (default)

  • 1: Solve feasibility problem: minimize sum of infeasibilities

  • 2: Solve feasibility problem: minimize largest infeasibility

  • 3: Solve feasibility problem: minimize sum of infeasibilities after scaling model

  • 4: Solve feasibility problem: minimize largest infeasibility after scaling model

• The effort level influences how much effort is used to find outliers in the (infeasible) data. It does not influence the running time of the method used.

• The option Element format determines the format used for printing elements in the message.

• The suffix .SuspicionLevel gets a value from the set AllSuspicionLevels, or remains empty if the parameter is not part of the infeasible data.

• The procedure GMP::Instance::GetInfeasibleData is not supported for generated mathematical programs created by one of the following functions:

  • GMP::Instance::GenerateRobustCounterpart,

  • GMP::Instance::GenerateStochasticProgram,

  • GMP::Instance::CreatePresolved,

  • GMP::Instance::CreateDual, or

  • GMP::Instance::CreateMasterMIP.

Example

Assume that ‘MP’ is a symbolic mathematical program and ‘pMessage’ a string parameter.

solve MP;

if ( MP.ProgramStatus = 'Infeasible'            or
     MP.ProgramStatus = 'InfeasibleOrUnbounded' ) then
    GMP::Instance::GetInfeasibleData( 'MP', AllParameters, pMessage,
                                      method: 4, textFormat: 1 );

    ! Change the font size for the HTML formatted text.
    pMessage := "<span style=\"font-size: 20px\">" + pMessage + "</span>";
endif;