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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/client.h"
#include "polymake/SparseMatrix.h"
#include "polymake/Graph.h"
namespace polymake { namespace graph {
namespace {
template <typename TGraph>
SparseMatrix<Int> incidence_matrix_impl(const GenericGraph<TGraph>& G, Int s = 1)
{
SparseMatrix<Int> E(G.top().nodes(), G.top().edges());
Int col = 0;
for (auto eit = entire(edges(G.top())); !eit.at_end(); ++eit, ++col) {
E(eit.from_node(), col) = s;
E(eit.to_node(), col) = 1;
}
return E;
}
} // end anonymous namespace
template <typename TGraph>
SparseMatrix<Int> incidence_matrix(const GenericGraph<TGraph>& p)
{
return incidence_matrix_impl(p.top(), 1);
}
template<typename TGraph>
SparseMatrix<Int> signed_incidence_matrix(const GenericGraph<TGraph>& p)
{
return incidence_matrix_impl(p.top(), -1);
}
template<typename Dir>
SparseMatrix<Int> incidence_matrix(BigObject p)
{
Graph<Dir> G = p.give("ADJACENCY");
return incidence_matrix_impl(G, 1);
}
template<typename Dir>
SparseMatrix<Int> signed_incidence_matrix(BigObject p)
{
Graph<Dir> G=p.give("ADJACENCY");
return incidence_matrix_impl(G, -1);
}
} }
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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