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////////////////////////////////////////////////////////////////////////////////
//
// SPXinterface.cc
//
// produced: 2003/01/15 jr
// last change: 2003/01/15 jr
//
////////////////////////////////////////////////////////////////////////////////
#ifdef HAVE_LIBSOPLEX
#include "SPXinterface.hh"
namespace topcom {
// constructors:
SPXinterface::SPXinterface(const Matrix& m, const LabelSet& support) :
_soplex_obj(),
_support(support) {
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "building soplex LP ..." << std::endl;
}
_soplex_obj.spxout.setVerbosity( soplex::SPxOut::ERROR );
_soplex_obj.setRealParam(_soplex_obj.FEASTOL, 0);
_soplex_obj.setRealParam(_soplex_obj.OPTTOL, 0);
_soplex_obj.setIntParam(_soplex_obj.SOLVEMODE, 2);
_soplex_obj.setIntParam(_soplex_obj.SYNCMODE, 1);
_soplex_obj.setIntParam(_soplex_obj.READMODE, 1);
_soplex_obj.setIntParam(_soplex_obj.CHECKMODE, 2);
for (size_type i = 0; i < m.coldim(); ++i) {
soplex::DSVectorRational row_vec;
bool nonempty = false;
for (size_type j = 0; j < m.rowdim(); ++j) {
// first, the row of the coefficient matrix of the LP has to be added;
// again, we have to use the coefficient matrix m in a transposed way;
// since soplex uses sparse structures, we just enter non zeroes:
if (m(j, i) != FieldConstants::ZERO) {
row_vec.add(j, __field_to_soplexrational(m(j, i)));
nonempty = true;
}
}
// next, we must construct a complete LP row from
// the coefficient vector, the right hand side and the sense;
// the right hand side is zero but we need strict feasibility,
// i.e., we seek an interior point of a homogeneous cone Ax > 0;
// because of homogenity, we can safely set the right hand side to one,
// since every solution x with Ax > 0 can be scaled to a solution y with Ay >= 1;
// moreover, the changing directions Ax <= -1 to Ax >= 1 in all inequalities at the same time
// leads to an equivalent problem because if y is feasible for Ax <= -1 then
// -y is feasible for Ax >= 1:
if (nonempty) {
_soplex_obj.addRowRational(soplex::LPRowRational(1, row_vec, soplex::infinity));
}
}
if (CommandlineOptions::debug()) {
std::lock_guard<std::mutex> lock(IO_sync::mutex);
std::cerr << "... done." << std::endl;
}
}
// functions:
bool SPXinterface::has_interior_point(Vector* heightsptr) {
if (CommandlineOptions::debug()) {
_soplex_obj.writeFileRational("SPX_LP_debugfile.lp");
}
static size_type idx = 0;
soplex::SPxSolver::Status stat;
// check feasibility with soplex library:
stat = _soplex_obj.solve();
bool infeasible(stat == soplex::SPxSolver::INFEASIBLE);
if (infeasible) {
return false;
}
else {
if (CommandlineOptions::output_heights()) {
soplex::VectorRational heights(_soplex_obj.numCols());
_soplex_obj.getPrimalRational(heights);
soplex::Rational maxheight(1);
for (parameter_type j = 0; j < heights.dim(); j++) {
const soplex::Rational x_j = heights[j];
if (maxheight - 1 < x_j) {
maxheight = x_j + 1;
}
}
for (parameter_type j = 0; j < heights.dim(); j++) {
const soplex::Rational x_j = heights[j];
if (_support.contains(j)) {
heightsptr->at(j) = __soplexrational_to_field(x_j);
}
else {
if (CommandlineOptions::debug()) {
std::cerr << std::endl << "-- point " << j << " unused, assigning height " << maxheight << " --" << std::endl;
}
heightsptr->at(j) = __soplexrational_to_field(maxheight);
}
}
}
return true;
}
}
}; // namespace topcom
#endif // HAVE_LIBSOPLEX
// eof SPXinterface.cc
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