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/*
* Copyright 2008-2009 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <cusp/detail/config.h>
namespace cusp
{
namespace precond
{
namespace aggregation
{
/* Compute a strength of connection matrix using the standard symmetric measure.
* An off-diagonal connection A[i,j] is strong iff::
*
* abs(A[i,j]) >= theta * sqrt( abs(A[i,i]) * abs(A[j,j]) )
*
* With the default threshold (theta = 0.0) all connections are strong.
*
* Note: explicit diagonal entries are always considered strong.
*/
template <typename Matrix1, typename Matrix2>
void symmetric_strength_of_connection(const Matrix1& A, Matrix2& S, const double theta = 0.0);
} // end namespace aggregation
} // end namespace precond
} // end namespace cusp
#include <cusp/precond/aggregation/detail/strength.inl>
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