CPXgetcallbacksosinfo

Note

This is an advanced routine. Advanced routines typically demand a thorough understanding of the algorithms used by ILOG CPLEX. Thus they incur a higher risk of incorrect behavior in your application, behavior that can be difficult to debug. Therefore, ILOG encourages you to consider carefully whether you can accomplish the same task by means of other Callable Library routines instead.

The routine CPXgetcallbacksosinfo accesses information about special ordered sets (SOSs) during MIP optimization from within user-written callbacks. This routine may be called only when the value of its wherefrom argument is one of these values:

CPX_CALLBACK_MIP_HEURISTIC,
CPX_CALLBACK_MIP_BRANCH,
CPX_CALLBACK_MIP_INCUMBENT, or
CPX_CALLBACK_MIP_CUT.

The information returned is for the original problem if the parameter CPX_PARAM_MIPCBREDLP is set to CPX_OFF before the call to CPXmipopt that calls the callback. Otherwise, it is for the presolved problem.

Example

 status = CPXgetcallbacksosinfo(env, curlp, wherefrom, 6, 4,
                                CPX_CALLBACK_INFO_SOS_IS_FEASIBLE,
                                &isfeasible);

See also the example admipex3.c in the standard distribution.

Table 1: Information Requested for a User-Written SOS Callback
Symbolic Constant	C Type	Meaning
`CPX_CALLBACK_INFO_SOS_NUM`	`int`	number of SOSs
`CPX_CALLBACK_INFO_SOS_TYPE`	`char`	one of the values in Table 4
`CPX_CALLBACK_INFO_SOS_SIZE`	`int`	size of SOS
`CPX_CALLBACK_INFO_SOS_IS_FEASIBLE`	`int`	1 if SOS is feasible 0 if SOS is not
`CPX_CALLBACK_INFO_SOS_MEMBER_INDEX`	`int`	variable index of memberth member of SOS
`CPX_CALLBACK_INFO_SOS_MEMBER_REFVAL`	`double`	reference value (weight) of this member

Table 2: SOS Types Returned when whichinfo = CPX_CALLBACK_INFO_SOS_TYPE
Symbolic Constant	SOS Type
`CPX_SOS1`	type 1
`CPX_SOS2`	type 2

A pointer to the CPLEX environment, as returned by CPXopenCPLEX.

The pointer passed to the user-written callback. This parameter must be the value of cbdata passed to the user-written callback.

An integer value indicating where the user-written callback was called from. This parameter must be the value of wherefrom passed to the user-written callback.

The index of the special ordered set (SOS) for which information is requested. SOSs are indexed from zero to (numsets - 1) where numsets is the result of calling this routine with a whichinfo value of CPX_CALLBACK_INFO_SOS_NUM.

The index of the member of the SOS for which information is requested.

An integer indicating which information is requested. Table 1 summarizes the possible values. Table 2 summarizes possible values returned when the type of information requested is the SOS type (that is, whichinfo = CPX_CALLBACK_INFO_SOS_TYPE).

A generic pointer to a variable of type double, int, or char. The variable represents the value returned by whichinfo. (The column C Type in the table indicates the type of various values returned by whichinfo.)

The routine returns zero if successful and nonzero if an error occurs. If the return value is nonzero, the requested value may not be available.

CPXgetcallbacksosinfo

Parameters:

Returns:

env	A pointer to the CPLEX environment, as returned by `CPXopenCPLEX`.
cbdata	The pointer passed to the user-written callback. This parameter must be the value of `cbdata` passed to the user-written callback.
wherefrom	An integer value indicating where the user-written callback was called from. This parameter must be the value of `wherefrom` passed to the user-written callback.
sosindex	The index of the special ordered set (SOS) for which information is requested. SOSs are indexed from zero to `(numsets - 1)` where `numsets` is the result of calling this routine with a `whichinfo` value of `CPX_CALLBACK_INFO_SOS_NUM`.
member	The index of the member of the SOS for which information is requested.
whichinfo	An integer indicating which information is requested. Table 1 summarizes the possible values. Table 2 summarizes possible values returned when the type of information requested is the SOS type (that is, `whichinfo` = `CPX_CALLBACK_INFO_SOS_TYPE`).
result_p	A generic pointer to a variable of type `double`, `int`, or `char`. The variable represents the value returned by `whichinfo`. (The column C Type in the table indicates the type of various values returned by `whichinfo`.)