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/* VertexConesWith4ti2.cpp -- Compute vertex cones with 4ti2
Copyright 2007 Matthias Koeppe
This file is part of LattE.
LattE is free software; you can redistribute it and/or modify it
under the terms of the version 2 of the GNU General Public License
as published by the Free Software Foundation.
LattE 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.
You should have received a copy of the GNU General Public License
along with LattE; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
// From 4ti2:
#include "groebner/BitSet.h"
#include "groebner/VectorArrayStream.h"
#include "groebner/LatticeBasis.h"
#include "groebner/RayAlgorithm.h"
#include "latte_gmp.h"
#include "latte_4ti2.h"
#include "VertexConesWith4ti2.h"
#include "dual.h"
#include "DualizationWith4ti2.h"
#include "print.h"
using namespace _4ti2_;
void
computeVertexConesWith4ti2(listVector* ineqs, int numOfVars,
bool &unbounded,
ConeConsumer &consumer)
{
unbounded = false;
listCone *cones = NULL;
int num_ineqs = lengthListVector(ineqs);
/* Create a matrix from the facets, with extra coordinates
at the front for slack variables. The 1 is related to the fact
that the vectors of MATRIX already have 1 + numOfVars entries.
*/
int lifted_dim = 1 + numOfVars + num_ineqs;
BitSet *rs = new BitSet(lifted_dim);
VectorArray *matrix
= rays_to_4ti2_VectorArray(ineqs, 1 + numOfVars,
/* num_homogenization_vars: */ num_ineqs,
/* num_extra_rows: */ 0);
/* Add negative identity matrix for the slack variables. */
{
int i;
for (i = 0; i<num_ineqs; i++) {
(*matrix)[i][i] = -1;
rs->set(i);
}
}
/* Make the homogenization coordinate (corresponding to the right-hand side) non-negative */
rs->set(num_ineqs);
#if 0
{
std::ofstream file("cone_for_4ti2_vertex_cones_computation");
file << matrix->get_number() << " " << lifted_dim << endl;
print(file, *matrix, 0, lifted_dim);
cerr << "Created file `cone_for_4ti2_vertex_cones_computation'" << endl;
}
#endif
VectorArray *rays = new VectorArray(0, matrix->get_size());
lattice_basis(*matrix, *rays);
VectorArray* subspace = new VectorArray(0, matrix->get_size());
RayAlgorithm algorithm;
algorithm.compute(*matrix, *rays, *subspace, *rs);
delete rs;
#if 0
{
std::ofstream file("4ti2_vertex_cones_computation_output");
file << rays->get_number() << " " << lifted_dim << "\n";
print(file, *rays, 0, lifted_dim);
cerr << "Created file `4ti2_vertex_cones_computation_output'" << endl;
}
#endif
assert(subspace->get_number() == 0); /* We assume polytopes,
thus a pointed
homogenization */
delete matrix;
delete subspace;
int num_rays = rays->get_number();
/* Walk through all rays of the homogenization; each gives a vertex
of the polytope. */
int i;
for (i = 0; i<num_rays; i++) {
ZZ denominator = convert_mpz_to_ZZ((*rays)[i][num_ineqs]);
if (denominator == 0) {
/* This ray corresponds to a ray of the (unbounded!) polyhedron;
ignore it. */
unbounded = true;
}
else {
listCone *cone = createListCone();
vec_ZZ numerator;
numerator.SetLength(numOfVars);
int j;
for (j = 0; j<numOfVars; j++)
numerator[j] = convert_mpz_to_ZZ((*rays)[i][num_ineqs + 1 + j]);
rationalVector *vertex_vector = new rationalVector(numerator, denominator);
cone->vertex = new Vertex(vertex_vector);
/* Compute the facets: */
/* Find incident facets.
They are the facets whose corresponding slack variables are
zero. */
listVector *ineq;
for (j = 0, ineq = ineqs; j<num_ineqs; j++, ineq = ineq->rest) {
if ((*rays)[i][j] == 0) {
/* Incident! */
vec_ZZ facet_vector;
facet_vector.SetLength(numOfVars);
int k;
for (k = 0; k<numOfVars; k++)
facet_vector[k] = - ineq->first[k + 1];
/* Cancel GCD: */
ZZ gcd;
for (k = 0; k<numOfVars; k++)
gcd = GCD(gcd, facet_vector[k]);
if (gcd != 0 && gcd != 1) {
for (k = 0; k<numOfVars; k++)
facet_vector[k] /= gcd;
}
cone->facets = new listVector(facet_vector, cone->facets);
}
}
/* FIXME: To cheaply compute the rays of the vertex cone, we need
to get hold of the adjacent rays of the current ray of the
homogenization.
For the moment, don't compute the rays. Later code will construct
them when needed.
*/
#if 0
printCone(cone, numOfVars);
#endif
consumer.ConsumeCone(cone);
}
}
delete rays;
}
listCone *
computeVertexConesWith4ti2(listVector* matrix, int numOfVars,
bool &unbounded)
{
CollectingConeConsumer ccc;
computeVertexConesWith4ti2(matrix, numOfVars, unbounded, ccc);
return ccc.Collected_Cones;
}
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