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========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Copyright (C) 2016-2021 OpenFOAM Foundation
\\/ M anipulation |
-------------------------------------------------------------------------------
License
This file is part of OpenFOAM.
OpenFOAM 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 3 of the License, or
(at your option) any later version.
OpenFOAM 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 OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
\*---------------------------------------------------------------------------*/
#include "LLTMatrix.H"
// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
template<class Type>
Foam::LLTMatrix<Type>::LLTMatrix()
{}
template<class Type>
Foam::LLTMatrix<Type>::LLTMatrix(const SquareMatrix<Type>& M)
{
decompose(M);
}
// * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * * //
template<class Type>
void Foam::LLTMatrix<Type>::decompose(const SquareMatrix<Type>& M)
{
SquareMatrix<Type>& LLT = *this;
// Initialise the LLT decomposition matrix to M
LLT = M;
const label m = LLT.m();
for (label i=0; i<m; i++)
{
for (label j=0; j<m; j++)
{
if (j > i)
{
LLT(i, j) = Zero;
continue;
}
Type sum = LLT(i, j);
for (label k=0; k<j; k++)
{
sum -= LLT(i, k)*LLT(j, k);
}
if (i > j)
{
LLT(i, j) = sum/LLT(j, j);
}
else if (sum > 0)
{
LLT(i, i) = sqrt(sum);
}
else
{
FatalErrorInFunction
<< "Cholesky decomposition failed, "
"matrix is not symmetric positive definite"
<< abort(FatalError);
}
}
}
}
template<class Type>
void Foam::LLTMatrix<Type>::solve
(
Field<Type>& x,
const Field<Type>& source
) const
{
// If x and source are different initialise x = source
if (&x != &source)
{
x = source;
}
const SquareMatrix<Type>& LLT = *this;
const label m = LLT.m();
for (label i=0; i<m; i++)
{
Type sum = source[i];
for (label j=0; j<i; j++)
{
sum = sum - LLT(i, j)*x[j];
}
x[i] = sum/LLT(i, i);
}
for (int i=m - 1; i >= 0; i--)
{
Type sum = x[i];
for (label j=i + 1; j<m; j++)
{
sum = sum - LLT(j, i)*x[j];
}
x[i] = sum/LLT(i, i);
}
}
template<class Type>
Foam::tmp<Foam::Field<Type>> Foam::LLTMatrix<Type>::solve
(
const Field<Type>& source
) const
{
tmp<Field<Type>> tx(new Field<Type>(this->m()));
Field<Type>& x = tx.ref();
solve(x, source);
return tx;
}
// ************************************************************************* //
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