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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2009, Ben Burton *
* For further details contact Ben Burton (bab@debian.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 of the *
* License, or (at your option) any later version. *
* *
* 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. *
* *
* You should have received a copy of the GNU General Public *
* License along with this program; if not, write to the Free *
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, *
* MA 02110-1301, USA. *
* *
**************************************************************************/
/* end stub */
#include <algorithm>
#include <cstdlib>
#include "triangulation/nisomorphism.h"
#include "triangulation/ntriangulation.h"
namespace regina {
NIsomorphism::NIsomorphism(const NIsomorphism& cloneMe) :
nTetrahedra(cloneMe.nTetrahedra),
mTetImage(cloneMe.nTetrahedra > 0 ?
new int[cloneMe.nTetrahedra] : 0),
mFacePerm(cloneMe.nTetrahedra > 0 ?
new NPerm[cloneMe.nTetrahedra] : 0) {
std::copy(cloneMe.mTetImage, cloneMe.mTetImage + nTetrahedra, mTetImage);
std::copy(cloneMe.mFacePerm, cloneMe.mFacePerm + nTetrahedra, mFacePerm);
}
void NIsomorphism::writeTextShort(std::ostream& out) const {
out << "Isomorphism between triangulations";
}
void NIsomorphism::writeTextLong(std::ostream& out) const {
for (unsigned i = 0; i < nTetrahedra; i++)
out << i << " -> " << mTetImage[i] << " (" << mFacePerm[i] << ")\n";
}
bool NIsomorphism::isIdentity() const {
for (unsigned t = 0; t < nTetrahedra; t++) {
if (mTetImage[t] != static_cast<int>(t))
return false;
if (! mFacePerm[t].isIdentity())
return false;
}
return true;
}
NTriangulation* NIsomorphism::apply(const NTriangulation* original) const {
if (original->getNumberOfTetrahedra() != nTetrahedra)
return 0;
if (nTetrahedra == 0)
return new NTriangulation();
NTetrahedron** tet = new NTetrahedron*[nTetrahedra];
unsigned long t;
int f;
for (t = 0; t < nTetrahedra; t++)
tet[t] = new NTetrahedron();
const NTetrahedron *myTet, *adjTet;
unsigned long adjTetIndex;
NPerm gluingPerm;
for (t = 0; t < nTetrahedra; t++) {
myTet = original->getTetrahedron(t);
for (f = 0; f < 4; f++)
if ((adjTet = myTet->adjacentTetrahedron(f))) {
// We have an adjacent tetrahedron.
adjTetIndex = original->tetrahedronIndex(adjTet);
gluingPerm = myTet->adjacentGluing(f);
// Make the gluing from one side only.
if (adjTetIndex > t || (adjTetIndex == t &&
gluingPerm[f] > f))
tet[mTetImage[t]]->joinTo(mFacePerm[t][f],
tet[mTetImage[adjTetIndex]],
mFacePerm[adjTetIndex] * gluingPerm *
mFacePerm[t].inverse());
}
}
NTriangulation* ans = new NTriangulation();
for (t = 0; t < nTetrahedra; t++)
ans->addTetrahedron(tet[t]);
return ans;
}
NIsomorphism* NIsomorphism::random(unsigned nTetrahedra) {
NIsomorphism* ans = new NIsomorphism(nTetrahedra);
// Randomly choose the destination tetrahedra.
unsigned i;
for (i = 0; i < nTetrahedra; i++)
ans->mTetImage[i] = i;
std::random_shuffle(ans->mTetImage, ans->mTetImage + nTetrahedra);
// Randomly choose the individual permutations.
for (i = 0; i < nTetrahedra; i++)
ans->mFacePerm[i] = NPerm::S4[rand() % 24];
return ans;
}
} // namespace regina
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