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XPRBgetslack

XPRBgetslack

Purpose
Get slack value for a constraint.
Synopsis
double XPRBgetslack(XPRBctr ctr);
Argument
ctr 
Reference to a constraint.
Return value
Slack value for the constraint, 0 in case of an error.
Example 
XPRBprob expl2;
XPRBctr ctr2;
XPRBarrvar ty1;
double slack;
   ...
expl2 = XPRBnewprob("example2");
ty1 = XPRBnewarrvar(expl2, 5, XPRB_PL, "arry1", 0, 500);
ctr2 = XPRBnewsum(expl2, "r2", ty1, XPRB_E, 9);
XPRBlpoptimize(expl2, "");
slack = XPRBgetslack(ctr2);
This obtains the slack value for the constraint ctr2.
Further information
This function returns the slack value for a constraint. The user may wish to test first whether this constraint is part of the problem, for instance by checking that the row number is non-negative.
If this function is called after completion of a global search and an integer solution has been found (that is, if function XPRBgetmipstat returns values XPRB_MIP_SOLUTION or XPRB_MIP_OPTIMAL), it returns the value in the best integer solution. If no integer solution is available after a global search this function outputs a warning and returns 0. In all other cases it returns the slack value in the last LP that has been solved. If this function is used during the execution of an optimization process (for instance in Optimizer library callback functions) it needs to be preceded by a call to XPRBsync with the flag XPRB_XPRS_SOL.
Related topics
XPRBgetact, XPRBgetdual, XPRBgetobjval, XPRBgetrcost, XPRBgetsol, XPRBsync.

Parent Topic BCL C library functions

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