CPXXaddindconstr and CPXaddindconstr

The routine CPXXaddindconstr/CPXaddindconstr adds an indicator constraint to the specified problem object.

int CPXXaddindconstr( CPXCENVptr env, CPXLPptr lp, CPXDIM indvar, int complemented, CPXDIM nzcnt, double rhs, int sense, CPXDIM const * linind, double const * linval, char const * indname_str )

int CPXaddindconstr( CPXCENVptr env, CPXLPptr lp, int indvar, int complemented, int nzcnt, double rhs, int sense, int const * linind, double const * linval, char const * indname_str )

Description

The routine CPXXaddindconstr/CPXaddindconstr adds an indicator constraint to the specified problem object. This routine may be called any time after a call to CPXXcreateprob/CPXcreateprob.

An indicator constraint is a linear constraint that is enforced only:

when an associated binary variable takes a value of 1, or
when an associated binary variable takes the value of 0 (zero) if the binary variable is complemented.

The linear constraint may be a less-than-or-equal-to constraint, a greater-than-or-equal-to constraint, or an equality constraint.

Table 1. Codes for the sense of a linear constraint
`sense`	= `'L'`	<= constraint
`sense`	= `'G'`	>= constraint
`sense`	= `'E'`	== constraint

Tip:

This routine adds only one indicator constraint at a time. Also, it can add only one type of indicator constraint (an IF constraint, designated in an LP format file as ->). When you want to add other types of indicator constraints, such as IfOnly (<-) or IfAndOnlyIf (< - >), or when you are building a model with many indicator constraints, you can use CPXXaddindconstraints and CPXaddindconstraints.

Arguments

env: A pointer to the CPLEX environment, as returned by CPXXopenCPLEX/CPXopenCPLEX.
lp: A pointer to a CPLEX LP problem object, as returned by CPXXcreateprob/CPXcreateprob.
indvar: The binary variable that acts as the indicator for this constraint.
complemented: A Boolean value that specifies whether the indicator variable is complemented. The linear constraint must be satisfied when the indicator takes a value of 1 (one) if the indicator is not complemented, and similarly, the linear constraint must be satisfied when the indicator takes a value of 0 (zero) if the indicator is complemented.
nzcnt: An integer that specifies the number of nonzero coefficients in the linear portion of the indicator constraint. This argument gives the length of the arrays linind and linval.
rhs: The righthand side value for the linear portion of the indicator constraint.
sense: The sense of the linear portion of the indicator constraint. Specify 'L' for <= or 'G' for >= or 'E' for ==.
linind: An array that with linval defines the linear portion of the indicator constraint.
linval: An array that with linind defines the linear portion of the indicator constraint. The nonzero coefficients of the linear terms must be stored in sequential locations in the arrays linind and linval from positions 0 to nzcnt-1. Each entry, linind[i], indicates the variable index of the corresponding coefficient, linval[i].
indname_str: The name of the constraint to be added. May be NULL, in which case the new constraint is assigned a default name if the indicator constraints already resident in the CPLEX problem object have names; otherwise, no name is associated with the constraint.

Return

The routine returns zero if successful and nonzero if an error occurs.

Example


 status = CPXaddindconstr (env, lp, indicator, complemented, nzcnt,
                           rhs, 'G', ind, val, newindname);