ILOG CPLEX C++ API 9.0 Reference Manual

IloCplex
public IloNum getDual(const IloRange range)
This method returns the dual value associated with constraint range in the current
solution of the invoking algorithm.
public void getDuals(IloNumArray val,
const IloRangeArray con)
This method puts the dual values associated with the ranges in the array con into the
array val. Array val is resized to the same size as array con, and val[i] will
contain the dual value for constraint con[i].
public IloNum getFormulationBigValue()
The method getFormulationBigValue returns the current setting of the large
value used to set a bound on otherwise unbounded expressions appearing in logical
constraints. Such a value is sometimes referred to as Big M.
By default, this value is 1e6. You can change that default setting by means of the
method setFormulationBigValue.
In order to transform a logical constraint automatically into an equivalent MIP
representation, it is sometimes necessary to set a finite upper or lower bound on an
otherwise unbounded term. When such a bound does not already exist, CPLEX uses the
value returned by this method for that purpose. For example, consider the following
disjunction (that is, or-statement):
(x == 1) || (x 2)
It is necessary to have an upper bound on x. If the upper bound on x is
IloInfinity, CPLEX will use the value returned by
getFormulationBigValue in the transformed representation of logical
formulations.
public IloNum getFormulationEpsValue()
This method returns the epsilon value that is used to model strict relations. In order to
model a strict inequality, such as x < b in a MIP, IloCplex uses x ≤ b - eps as a
surrogate, where eps is the value returned by this method.
public void getIIS(IloCplex::IISStatusArray cstat,
IloNumVarArray var,
IloCplex::IISStatusArray rstat,
IloConstraintArray rng)
If an LP model has been proven to be infeasible, this method can compute an
irreducibly inconsistent set (IIS). The variables and range constraints in the IIS are
returned in the arrays var and rng, respectively.
ILOG CPLEX C++ API 9.0 REFERENCE M ANUAL 61