bool SOS1Handler::isFeasible(ConstSolutionPtr sol, RelaxationPtr rel, bool &,
double &)
{
SOSPtr sos;
bool isfeas = true;
int nz;
const double* x = sol->getPrimal();
for (SOSConstIterator siter=rel->sos1Begin(); siter!=rel->sos1End();
++siter) {
sos = *siter;
nz = 0;
for (VariableConstIterator viter = sos->varsBegin(); viter!=sos->varsEnd();
++viter) {
if (x[(*viter)->getIndex()]>zTol_) {
++nz;
if (nz>1) {
isfeas = false;
break;
}
}
}
if (false == isfeas) {
break;
}
}
#if SPEW
logger_->msgStream(LogDebug) << me_ << "isFeasible = " << isfeas
<< std::endl;
#endif
return isfeas;
}
void SOS1Handler::getBranchingCandidates(RelaxationPtr rel,
const DoubleVector &x,
ModVector &, BrVarCandSet &,
BrCandVector &gencands,
bool &is_inf)
{
SOSConstIterator siter;
VariableConstIterator viter;
VariablePtr var;
SOSPtr sos;
double parsum;
VarVector lvars, rvars;
int nz;
double nzsum;
double nzval;
SOSBrCandPtr br_can;
for (siter=rel->sos1Begin(); siter!=rel->sos1End(); ++siter) {
sos = *siter;
getNzNumSum_(sos, x, &nz, &nzsum);
if (nz>1) {
parsum = 0.0;
lvars.clear();
rvars.clear();
viter = sos->varsBegin();
for (; viter!=sos->varsEnd(); ++viter) {
var = *viter;
if (var->getUb()-var->getLb()>zTol_) {
nzval = x[var->getIndex()];
if ((parsum + nzval) < 0.5*nzsum) {
lvars.push_back(var);
parsum += nzval;
} else if (nzval+parsum - nzsum/2 < nzsum/2 - parsum) {
lvars.push_back(var);
parsum += nzval;
++viter;
break;
} else {
break;
}
}
}
for (; viter!=sos->varsEnd(); ++viter) {
var = *viter;
if (var->getUb()-var->getLb()>zTol_) {
rvars.push_back(*viter);
}
}
br_can = (SOSBrCandPtr) new SOSBrCand(sos, lvars, rvars, parsum,
nzsum-parsum);
br_can->setDir(DownBranch);
br_can->setScore(20.0*(lvars.size()-1)*(rvars.size()-1));
gencands.push_back(br_can);
#if SPEW
logger_->msgStream(LogDebug) << me_ << sos->getName() << " is a "
<< " branching candidate." << std::endl
<< me_ << "left branch has variables ";
for (viter = lvars.begin(); viter!=lvars.end(); ++viter) {
logger_->msgStream(LogDebug) << (*viter)->getName() << " ";
}
logger_->msgStream(LogDebug) << std::endl
<< me_ << "left sum = " << parsum
<< std::endl
<< me_ << "right branch has variables ";
for (viter = rvars.begin(); viter!=rvars.end(); ++viter) {
logger_->msgStream(LogDebug) << (*viter)->getName() << " ";
}
logger_->msgStream(LogDebug) << std::endl
<< me_ << "right sum = " << nzsum - parsum
<< std::endl;
#endif
} else {
#if SPEW
logger_->msgStream(LogDebug) << me_ << sos->getName() << " is not a "
<< " branching candidate." << std::endl;
#endif
}
}
is_inf = false;
}
