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### GRBcbstoponemultiobj

 int GRBcbstoponemultiobj ( GRBmodel *model, void* cbdata, int objnum )

Interrupt the optimization process of one of the optimization steps in a multi-objective MIP problem without stopping the hierarchical optimization process. Note that this routine can only be called for multi-objective MIP models and when the where value on the callback routine is not equal to GRB_CB_MULTIOBJ (see the Callback Codes section for more information).

You would typically stop a multi-objective optimization step by querying the last finished number of multi-objectives steps, and using that number to stop the current step and move on to the next hierarchical objective (if any) as shown in the following example:

Example usage:

#include <time.h>

typedef struct {
int    objcnt;
time_t starttime;
} usrdata_t;

int mycallback(GRBmodel *model,
void     *cbdata,
int       where,
void     *usrdata)
{
int error = 0;
usrdata_t *ud = (usrdata_t*)usrdata;

if (where == GRB_CB_MULTIOBJ) {
/* get current objective number */
error = GRBcbget(cbdata, where, MULTIOBJ_OBJCNT, (void*)&ud->objcnt);
if (error) goto QUIT;

/* reset start time to current time */
ud->starttime = time();

} else if (time() - ud->starttime > BIG ||
/* takes too long or good enough */) {
/* stop only this optimization step */
error = GRBcbstoponemultiobj(model, cbdata, ud->objcnt);
if (error) goto QUIT;
}

QUIT:
return error;
}


You should refer to the section on Multiple Objectives for information on how to specify multiple objective functions and control the trade-off between them.

Return value:

A non-zero return value indicates that a problem occurred while stopping the multi-objective step specified by objcnt. Refer to the Error Code table for a list of possible return values. Details on the error can be obtained by calling GRBgeterrormsg.

Arguments:

model: The model argument that was passed into the user callback by the Gurobi optimizer. This argument must be passed unmodified from the user callback to GRBcbstoponemultiobj().

cbdata: The cbdata argument that was passed into the user callback by the Gurobi optimizer. This argument must be passed unmodified from the user callback to GRBcbstoponemultiobj().

objnum: The number of the multi-objective optimization step to interrupt. For processes running locally, this argument can have the special value -1, meaning to stop the current step.