[Coin-discuss] Using CbcHeuristicFPump outside branch and cut

[James Gibbons]

Hi,

Hopefully this will be my last question for a bit. I've found that using CbcHeuristicFPump finds a good solution for my problem. Unfortunately, it then slows down the rest of branchAndBound(). The documentation recommends using it outside branch and cut, but I can't work out how to do this. My attempt is at the end of this email. From the source code it looks as if CbcHeuristicFPump::solution will always return 0 using my code because model_->getCurrentPassNumber() (line 88 of CbcHeuristicFPump.cpp) will always be 0. I tried the naive bodge of changing line 90 to if (!atRoot||passNumber>1) but this caused a crash. Is there a way around this?

BTW there is a documentation error in CBCHeuristicFPump.hpp, line 36, which I *think* gets 1 and 0 the wrong way around.

Thanks,
James

My code:

CbcModel model(*solver1);
CbcHeuristicFPump heur0(model);

double heurObjVal(1.0e50);
double *heurSol;
heur4.setWhen(3);
model.addHeuristic(&heur0);

int heurState = model.heuristic(0)->solution(heurObjVal,heurSol);
if(heurState!=0) {
    model.setBestSolution(CBC_HEURISTIC_SOLUTION,heurObjVal,heurSol);
}
model.heuristic(0)->setWhen(0);     //turn it off

model.branchAndBound();


-- 
Dr James Gibbons
Research Fellow
Division of Agricultural & Environmental Sciences
School of Biosciences
University of Nottingham
Sutton Bonington Campus
Loughborough
LE12 5RD

direct line: 0115 9516081
fax:           0115 9516060
e-mail:       james.gibbons at nottingham.ac.uk

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