PreconditionerBlockJacobi.hpp

/*
 * ------------------------------------------------------------------------------------------------------------
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 * Copyright (c) 2016-2024 Lawrence Livermore National Security LLC
 * Copyright (c) 2018-2024 Total, S.A
 * Copyright (c) 2018-2024 The Board of Trustees of the Leland Stanford Junior University
 * Copyright (c) 2023-2024 Chevron
 * Copyright (c) 2019-     GEOS/GEOSX Contributors
 * All rights reserved
 *
 * See top level LICENSE, COPYRIGHT, CONTRIBUTORS, NOTICE, and ACKNOWLEDGEMENTS files for details.
 * ------------------------------------------------------------------------------------------------------------
 */
 
#ifndef GEOS_LINEARALGEBRA_SOLVERS_PRECONDITIONERBLOCKJACOBI_HPP_
#define GEOS_LINEARALGEBRA_SOLVERS_PRECONDITIONERBLOCKJACOBI_HPP_
 
#include "linearAlgebra/common/LinearOperator.hpp"
#include "linearAlgebra/common/PreconditionerBase.hpp"
#include "denseLinearAlgebra/interfaces/blaslapack/BlasLapackLA.hpp"
 
namespace geos
{
 
template< typename LAI >
class PreconditionerBlockJacobi : public PreconditionerBase< LAI >
{
public:
 
  using Base = PreconditionerBase< LAI >;
 
  using Vector = typename Base::Vector;
 
  using Matrix = typename Base::Matrix;
 
  PreconditionerBlockJacobi( localIndex const & blockSize = 0 )
    : m_blockDiag{}
  {
    m_blockSize = blockSize;
  }
 
  virtual void setup( Matrix const & mat ) override
  {
    GEOS_LAI_ASSERT( mat.ready() );
    GEOS_LAI_ASSERT_GT( m_blockSize, 0 );
    GEOS_LAI_ASSERT_EQ( mat.numLocalRows() % m_blockSize, 0 );
    GEOS_LAI_ASSERT_EQ( mat.numLocalCols() % m_blockSize, 0 );
 
    PreconditionerBase< LAI >::setup( mat );
 
    m_blockDiag.createWithLocalSize( mat.numLocalRows(), mat.numLocalCols(), m_blockSize, mat.comm() );
    m_blockDiag.open();
 
    array1d< globalIndex > idxBlk( m_blockSize );
    array2d< real64 > values( m_blockSize, m_blockSize );
    array2d< real64 > valuesInv( m_blockSize, m_blockSize );
    array1d< globalIndex > cols;
    array1d< real64 > vals;
    for( globalIndex i = mat.ilower(); i < mat.iupper(); i += m_blockSize )
    {
      values.zero();
      for( localIndex j = 0; j < m_blockSize; ++j )
      {
        globalIndex const iRow = i + LvArray::integerConversion< globalIndex >( j );
        idxBlk[j] = iRow;
        localIndex const rowLength = mat.rowLength( iRow );
        cols.resize( rowLength );
        vals.resize( rowLength );
        mat.getRowCopy( iRow, cols, vals );
        for( localIndex k = 0; k < rowLength; ++k )
        {
          localIndex const jCol = LvArray::integerConversion< localIndex >( cols[k]-i );
          if( cols[k] >= i && cols[k] < i+LvArray::integerConversion< globalIndex >( m_blockSize ) )
          {
            values( j, jCol ) = vals[k];
          }
        }
      }
      BlasLapackLA::matrixInverse( values, valuesInv );
      m_blockDiag.insert( idxBlk, idxBlk, valuesInv );
    }
    m_blockDiag.close();
  }
 
  virtual void clear() override
  {
    m_blockDiag.reset();
  }
 
  virtual void apply( Vector const & src,
                      Vector & dst ) const override
  {
    GEOS_LAI_ASSERT( m_blockDiag.ready() );
    GEOS_LAI_ASSERT_EQ( this->numGlobalRows(), dst.globalSize() );
    GEOS_LAI_ASSERT_EQ( this->numGlobalCols(), src.globalSize() );
 
    m_blockDiag.apply( src, dst );
  }
 
  virtual bool hasPreconditionerMatrix() const override
  {
    GEOS_LAI_ASSERT( m_blockDiag.ready() );
    return true;
  }
 
  virtual Matrix const & preconditionerMatrix() const override
  {
    GEOS_LAI_ASSERT( m_blockDiag.ready() );
    return m_blockDiag;
  }
 
private:
 
  Matrix m_blockDiag;
 
  localIndex m_blockSize = 0;
};
 
}
 
#endif //GEOS_LINEARALGEBRA_SOLVERS_PRECONDITIONERBLOCKJACOBI_HPP_