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/* Copyright (c) 1997-2024
Ewgenij Gawrilow, Michael Joswig, and the polymake team
Technische Universität Berlin, Germany
https://polymake.org
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version: http://www.gnu.org/licenses/gpl.txt.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
--------------------------------------------------------------------------------
*/
#pragma once
#include "polymake/Rational.h"
#include "polymake/SparseMatrix.h"
#include "polymake/SparseVector.h"
#include "polymake/Array.h"
#include "polymake/Vector.h"
#include "polymake/Set.h"
#include <fstream>
#include "polymake/linalg.h"
namespace polymake { namespace polytope {
namespace {
template<typename Scalar, std::enable_if_t<!std::is_same<Rational, Scalar>::value, int> = 42>
void multiply_by_lcm_denom(SparseVector<Scalar>& v){
}
template<typename Scalar, std::enable_if_t<std::is_same<Rational, Scalar>::value, int> = 42>
void multiply_by_lcm_denom(SparseVector<Scalar>& v){
Integer s = lcm(denominators(v));
if(s > 10000) return; // If the lcm is higher than 10000, it might be better to just stay with the fractions
auto e = entire(v.top());
while (!e.at_end()){
*e = *e*s;
e++;
}
}
template <typename VectorType>
void print_row(std::ostream& os,
const std::string& tag,
Int index,
const GenericVector<VectorType>& v,
const Array<std::string>& variable_names,
const char* relop = nullptr)
{
if (v == unit_vector<typename VectorType::element_type>(v.dim(),0)) // don't print the line " 0 >= -1 "
return;
SparseVector<typename VectorType::element_type> tmp(v);
// multiply inequality/equation by lcm
if (tag=="ie" || tag=="eq") {
multiply_by_lcm_denom(tmp);
}
auto e = entire(tmp.top());
typename VectorType::element_type free_term(0);
if (!e.at_end() && e.index() == 0) {
free_term=*e; ++e;
}
os << " " << tag;
if (tag != "obj") os << index;
os << ":";
while (!e.at_end()) {
os << ' ' << std::setiosflags(std::ios::showpos) << convert_to<double>(*e) << std::resetiosflags(std::ios::showpos)
<< ' ' << variable_names[e.index()-1];
++e;
}
if (relop) {
os << ' ' << relop << ' ' << convert_to<double>(-free_term);
} else if (!is_zero(free_term)) {
os << ' ' << std::setiosflags(std::ios::showpos) << convert_to<double>(free_term) << std::resetiosflags(std::ios::showpos);
}
os << '\n';
}
} // end anonymous namespace
template<typename Scalar, bool is_lp>
void print_lp(BigObject p, BigObject lp, const bool maximize, std::ostream& os)
{
const SparseMatrix<Scalar>
IE = p.give("FACETS | INEQUALITIES"),
EQ = p.lookup("AFFINE_HULL | EQUATIONS");
const SparseVector<Scalar> LO = lp.give("LINEAR_OBJECTIVE");
const Int amb_dim = std::max(IE.cols(), EQ.cols());
const Int n_variables = amb_dim-1;
// Empty inequality matrix implies that these are facets.
// In polymake this only appears for the empty polytope
// but this cannot be encoded properly in an LP file.
// Note: this will not trigger a feasibility check
if (p.exists("FEASIBLE") && !p.lookup("FEASIBLE") ||
IE.rows() == 0 && EQ.rows() == 0)
throw std::runtime_error("poly2lp: input is not known to be infeasible");
Array<std::string> variable_names;
if (lp.get_attachment("COORDINATE_LABELS") >> variable_names) {
if (variable_names.size() != n_variables)
throw std::runtime_error("dimension mismatch between the polytope and COORDINATE_LABELS");
} else {
variable_names.resize(n_variables);
for (Int j=0; j < n_variables; ++j)
variable_names[j]='x' + std::to_string(j+1);
}
Array<bool> integers(1);
if(is_lp){
Array<bool> tmp = lp.get_attachment("INTEGER_VARIABLES");
// this attachment might omit the homogenization coordinate
if (tmp.size() == amb_dim-1)
integers.append(tmp);
else
integers = tmp;
} else {
integers.resize(amb_dim);
Set<Int> tmp = lp.give("INTEGER_VARIABLES");
for(const auto& e : tmp){
integers[e] = true;
}
}
os << std::setprecision(16)
<< (maximize ? "MAXIMIZE\n" : "MINIMIZE\n");
print_row(os, "obj", 0, LO, variable_names);
os << "Subject To\n";
for (auto ie=entire(rows(IE)); !ie.at_end(); ++ie) {
print_row(os, "ie", ie.index(), *ie, variable_names, ">=");
}
for (auto eq=entire(rows(EQ)); !eq.at_end(); ++eq) {
print_row(os, "eq", eq.index(), *eq, variable_names, "=");
}
os << "BOUNDS\n";
for (Int i = 0; i < n_variables; ++i)
os << " " << variable_names[i] << " free\n";
if (!integers.empty()) {
os << "GENERAL\n";
for (Int i = 1; i < integers.size(); ++i)
if (integers[i]) os << " " << variable_names[i-1] << '\n';
}
os << "END" << endl;
}
} }
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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