AMG Class Reference

#include <AMG.h>

Inheritance diagram for AMG:

Collaboration diagram for AMG:

Public Types
enum	CycleType { V_CYCLE, W_CYCLE, F_CYCLE }
enum	SmootherType { GAUSS_SEIDEL, JACOBI }

Public Member Functions
	AMG ()
virtual	~AMG ()
	DEFINE_TYPENAME ("AMG")
virtual MFRPtr	solve (LinearSystem &ls)
virtual void	smooth (LinearSystem &ls)
virtual void	setMergeLevelSize (int ls_size)
void	redirectPrintToFile (const string &fname)
void	redirectPrintToScreen ()
int	getTotalIterations () const
virtual void	cleanup ()
Public Member Functions inherited from LinearSolver
	LinearSolver ()

Public Attributes
int	maxCoarseLevels
int	nPreSweeps
int	nPostSweeps
int	coarseGroupSize
double	weightRatioThreshold
CycleType	cycleType
SmootherType	smootherType
bool	scaleCorrections
Public Attributes inherited from LinearSolver
int	nMaxIterations
int	verbosity
double	relativeTolerance
double	absoluteTolerance

Private Member Functions
	AMG (const AMG &)
void	createCoarseLevels ()
void	doSweeps (const int nSweeps, const int level)
void	cycle (CycleType cycleType, const int level)
void	flipComm ()

Private Attributes
LinearSystem *	_finestLinearSystem
vector< shared_ptr < LinearSystem > >	_coarseLinearSystems
shared_ptr< LinearSystemMerger >	_mergeLS
int	_mergeLevelSize
int	_mergeLevel
bool	_isMerge
int	_totalIterations
streambuf *	m_psbuf
streambuf *	m_backup
ofstream	m_filestr
bool	_isCOMMWORLD

Static Private Attributes
static int	amg_indx = 0

Detailed Description

Solve a linear system using algebraic multigrid.

Definition at line 27 of file AMG.h.

Member Enumeration Documentation

enum AMG::CycleType

Enumerator
V_CYCLE
W_CYCLE
F_CYCLE

Definition at line 31 of file AMG.h.

    {
      V_CYCLE,
      W_CYCLE,
      F_CYCLE
    };

enum AMG::SmootherType

Enumerator
GAUSS_SEIDEL
JACOBI

Definition at line 38 of file AMG.h.

    {
      GAUSS_SEIDEL,
      JACOBI
    };

Constructor & Destructor Documentation

AMG::AMG

(

)

Definition at line 15 of file AMG.cpp.

References logCtor.

         :
  maxCoarseLevels(30),
  nPreSweeps(0),
  nPostSweeps(1),
  coarseGroupSize(2),
  weightRatioThreshold(0.65),
  cycleType(V_CYCLE),
  smootherType(GAUSS_SEIDEL),
  scaleCorrections(true),
  _finestLinearSystem(0),
  _mergeLevelSize(0),
  _mergeLevel(-1),
  _isMerge(false),
  _totalIterations(0),
#ifdef FVM_PARALLEL
  _commTarget(MPI::COMM_WORLD),
#endif
  _isCOMMWORLD(true)
{
  logCtor();
  
}

AMG::~AMG ( )

virtual

Definition at line 38 of file AMG.cpp.

References logDtor.

{
  logDtor();
}

AMG::AMG ( const AMG &  )

private

Member Function Documentation

void AMG::cleanup ( )

virtual

Implements LinearSolver.

Definition at line 213 of file AMG.cpp.

References _coarseLinearSystems, and _finestLinearSystem.

{
  _finestLinearSystem = 0;
  _coarseLinearSystems.clear();
}

void AMG::createCoarseLevels ( )

private

Definition at line 150 of file AMG.cpp.

References _coarseLinearSystems, _finestLinearSystem, _isMerge, _mergeLevel, _mergeLevelSize, _mergeLS, coarseGroupSize, LinearSystem::createCoarse(), flipComm(), MultiFieldMatrix::getLocalSize(), LinearSystem::getMatrix(), LinearSystem::isSymmetric, maxCoarseLevels, LinearSolver::verbosity, and weightRatioThreshold.

Referenced by smooth(), and solve().

{

  _coarseLinearSystems.clear();
  for(int n=0; n<maxCoarseLevels; n++)
  {
      LinearSystem& fineLS = (n == 0) ?
        *_finestLinearSystem : *_coarseLinearSystems[n-1];
      shared_ptr<LinearSystem>
        coarseLS(fineLS.createCoarse(coarseGroupSize,weightRatioThreshold));

      coarseLS->isSymmetric = fineLS.isSymmetric;

     int isContinue =  int( fineLS.getMatrix().getLocalSize() != coarseLS->getMatrix().getLocalSize() );
#ifdef FVM_PARALLEL     
     _commTarget.Allreduce(MPI::IN_PLACE, &isContinue, 1, MPI::INT, MPI::SUM);
#endif     
     if ( isContinue == 0 )
            break;
          
#ifdef FVM_PARALLEL
     _coarseLinearSystems.push_back(coarseLS);
       
      int min_size = coarseLS->getMatrix().getMinSize( _commTarget );


      if ( verbosity > 1 && MPI::COMM_WORLD.Get_rank() == 0 )
        cout << " proc_id = " << MPI::COMM_WORLD.Get_rank() << "  Created coarse level " << n << " of size "
             << min_size  << endl;

      if ( min_size <= 3  )
        break;

      if ( coarseLS->getMatrix().getMergeSize( _commTarget ) < _mergeLevelSize &&  _mergeLevel == -1  && _isMerge ){
         _mergeLevel = n+1;
         set<int> group;
         int size = MPI::COMM_WORLD.Get_size();
         for ( int i = 0; i < size; i++ )
            group.insert(i);

         _mergeLS = shared_ptr<LinearSystemMerger> ( new LinearSystemMerger( 0, group, *coarseLS ) );
         _mergeLS->gatherMatrix();
         _coarseLinearSystems.push_back( _mergeLS->getLS() );
          n++;
          flipComm(); //this change to COMM_WORLD to one-processedGROUP 
      } 

#endif 

#ifndef FVM_PARALLEL
    if ( coarseLS->getMatrix().getSize() <= 3 )
       break;
    if ( verbosity > 1 )
        cout << "Created coarse level " << n << " of size " << coarseLS->getMatrix().getSize() << endl;
    _coarseLinearSystems.push_back(coarseLS);
#endif

  }


}

void AMG::cycle ( CycleType  cycleType, const int  level  )

private

Definition at line 71 of file AMG.cpp.

References _coarseLinearSystems, _finestLinearSystem, _mergeLevel, _mergeLS, MultiFieldMatrix::computeResidual(), MultiFieldMatrix::correctSolution(), doSweeps(), MultiField::dotWith(), F_CYCLE, LinearSystem::getB(), LinearSystem::getCoarseIndex(), LinearSystem::getDelta(), LinearSystem::getMatrix(), LinearSystem::getResidual(), MultiFieldMatrix::injectResidual(), LinearSystem::isSymmetric, nPostSweeps, nPreSweeps, MultiFieldMatrix::quadProduct(), scaleCorrections, V_CYCLE, W_CYCLE, and MultiField::zero().

Referenced by smooth(), and solve().

{
  doSweeps(nPreSweeps,level);

  if (level < (int)_coarseLinearSystems.size())
  {
      LinearSystem& fineLS = (level == 0) ?
        *_finestLinearSystem : *_coarseLinearSystems[level-1];


      LinearSystem& coarseLS = *_coarseLinearSystems[level];


      MultiFieldMatrix& fineMatrix = fineLS.getMatrix();

      fineMatrix.computeResidual(fineLS.getDelta(),fineLS.getB(),fineLS.getResidual());
      coarseLS.getB().zero();
      coarseLS.getDelta().zero();

      fineMatrix.injectResidual(fineLS.getCoarseIndex(),
                                fineLS.getResidual(),
                                coarseLS.getB());
 
      int nextLevel = level+1;
#ifdef  FVM_PARALLEL
      if ( nextLevel == _mergeLevel ) 
      { 
          _mergeLS->gatherB();
          nextLevel++;
      }
#endif
     //if ( level == 4 ) 
     //   cycleType = W_CYCLE;

     cycle(cycleType,nextLevel);

      if (cycleType == W_CYCLE)
        cycle(W_CYCLE,nextLevel);
      else if (cycleType == F_CYCLE)
        cycle(V_CYCLE,nextLevel);

#ifdef  FVM_PARALLEL
      if ( level+1 == _mergeLevel ) {
          _mergeLS->scatterDelta();
      }
#endif

      MFRPtr scale;
      if (coarseLS.isSymmetric && scaleCorrections)
      {
          const MultiField& x = coarseLS.getDelta();
          const MultiField& b = coarseLS.getB();
          const MultiFieldMatrix& A = coarseLS.getMatrix();
          MFRPtr xb =  x.dotWith(b);
          xb->reduceSum();

          MFRPtr mxb = -(*xb);
          MFRPtr xTAx = A.quadProduct(x);

          xTAx->reduceSum();
          
          scale = (*mxb)/(*xTAx);
          scale->limit(1.0, 1.0);
          
      }

      fineMatrix.correctSolution(fineLS.getCoarseIndex(),
                                 fineLS.getDelta(),
                                 scale,
                                 coarseLS.getDelta())   ;


  }

doSweeps(nPostSweeps,level);
  
}

AMG::DEFINE_TYPENAME

(

"AMG"

)

void AMG::doSweeps ( const int  nSweeps, const int  level  )

private

Definition at line 44 of file AMG.cpp.

References _coarseLinearSystems, _finestLinearSystem, MultiFieldMatrix::forwardGS(), GAUSS_SEIDEL, LinearSystem::getB(), LinearSystem::getDelta(), LinearSystem::getMatrix(), LinearSystem::getResidual(), MultiFieldMatrix::Jacobi(), MultiFieldMatrix::reverseGS(), and smootherType.

Referenced by cycle().

{

  LinearSystem& ls = (level == 0) ?
    *_finestLinearSystem : *_coarseLinearSystems[level-1];

  const MultiFieldMatrix& m = ls.getMatrix();
  MultiField& delta = ls.getDelta();
  const MultiField& b = ls.getB();
  MultiField& r = ls.getResidual();

  for(int i=0; i<nSweeps; i++)
  {
      if (smootherType == GAUSS_SEIDEL)
      {
          m.forwardGS(delta,b,r);
          m.reverseGS(delta,b,r);
      }
      else
      {
          m.Jacobi(delta,b,r);
          m.Jacobi(delta,b,r);
      }
  }
}

void AMG::flipComm ( )

private

Definition at line 303 of file AMG.cpp.

References _isCOMMWORLD.

Referenced by createCoarseLevels().

{

#ifdef FVM_PARALLEL
   if ( _isCOMMWORLD ){
      int color   = ( MPI::COMM_WORLD.Get_rank() == 0 );
      int key     = MPI::COMM_WORLD.Get_rank();
      _commTarget = MPI::COMM_WORLD.Split( color, key );
      _isCOMMWORLD = !_isCOMMWORLD;
   } else {
      _commTarget = MPI::COMM_WORLD;
      _isCOMMWORLD = !_isCOMMWORLD;
   }
#endif



}

int AMG::getTotalIterations ( ) const

inline

Definition at line 69 of file AMG.h.

{ return _totalIterations;}

void AMG::redirectPrintToFile

(

const string &

fname

)

Definition at line 325 of file AMG.cpp.

References m_backup, m_filestr, and m_psbuf.

                                              {
    m_filestr.open ( fname.c_str() );
    m_backup = cout.rdbuf();     // back up cout's streambuf
    m_psbuf = m_filestr.rdbuf();   // get file's streambuf
    cout.rdbuf(m_psbuf); 
}

void AMG::redirectPrintToScreen

(

)

Definition at line 334 of file AMG.cpp.

References m_backup, and m_filestr.

                            {
   cout.rdbuf(m_backup);        // restore cout's original streambuf
   m_filestr.close();
}

virtual void AMG::setMergeLevelSize ( int  ls_size )

inlinevirtual

Definition at line 53 of file AMG.h.

                                             { 
#ifdef FVM_PARALLEL
      //_mergeLevelSize = ceil(  double(ls_size) / double(MPI::COMM_WORLD.Get_size()) ); 
       _mergeLevelSize = ls_size;
      _isMerge = true;
#endif

#ifndef FVM_PARALLEL
      _mergeLevelSize = ls_size;
      cout << " you can not set mergeLevelSize in serial version !!!!!!!!!!! " << endl;
      abort();
#endif
}

void AMG::smooth ( LinearSystem &  ls )

virtual

Implements LinearSolver.

Definition at line 286 of file AMG.cpp.

References _finestLinearSystem, createCoarseLevels(), cycle(), and cycleType.

{
  if (_finestLinearSystem != &ls)
  {
      _finestLinearSystem = &ls;
      createCoarseLevels( );
  }
  _finestLinearSystem = &ls;

  {
      cycle(cycleType,0);
  }
}

MFRPtr AMG::solve ( LinearSystem &  ls )

virtual

Implements LinearSolver.

Definition at line 220 of file AMG.cpp.

References _finestLinearSystem, _totalIterations, LinearSolver::absoluteTolerance, MultiFieldMatrix::computeResidual(), createCoarseLevels(), cycle(), cycleType, LinearSystem::getB(), LinearSystem::getDelta(), LinearSystem::getMatrix(), MultiField::getOneNorm(), LinearSystem::getResidual(), LinearSolver::nMaxIterations, LinearSolver::relativeTolerance, MultiField::sync(), and LinearSolver::verbosity.

Referenced by main().

{
    if (_finestLinearSystem != &ls)
     {
       _finestLinearSystem = &ls;
       createCoarseLevels();
     }
    _finestLinearSystem = &ls;


  const MultiFieldMatrix& finestMatrix = _finestLinearSystem->getMatrix();
  finestMatrix.computeResidual(_finestLinearSystem->getDelta(),
                               _finestLinearSystem->getB(),
                               _finestLinearSystem->getResidual());

  MFRPtr rNorm0(_finestLinearSystem->getResidual().getOneNorm());

#ifdef FVM_PARALLEL
  if (verbosity >0 && MPI::COMM_WORLD.Get_rank() == 0 )
    cout << "0: " << *rNorm0 <<  endl;
#endif

#ifndef FVM_PARALLEL
   if ( verbosity > 0 )
      cout << "0: " << *rNorm0 << endl;
#endif

  if (*rNorm0 < absoluteTolerance )
    return rNorm0;

  for(int i=1; i<nMaxIterations; i++)
  {
      _totalIterations++;
      cycle(cycleType,0);
      finestMatrix.computeResidual(_finestLinearSystem->getDelta(),
                                   _finestLinearSystem->getB(),
                                   _finestLinearSystem->getResidual());
      MFRPtr rNorm(_finestLinearSystem->getResidual().getOneNorm());
      MFRPtr normRatio(rNorm->normalize(*rNorm0));

#ifndef FVM_PARALLEL
    if (verbosity >0  )
        cout << i << ": " <<  *rNorm << endl;


#endif

   
#ifdef FVM_PARALLEL
     if (*rNorm < absoluteTolerance || *normRatio < relativeTolerance || i == nMaxIterations-1)
        if (verbosity >0 && MPI::COMM_WORLD.Get_rank() == 0  )
        cout <<i << ": " <<   *rNorm << endl;
#endif

      if (*rNorm < absoluteTolerance || *normRatio < relativeTolerance)
         break;

  }

  _finestLinearSystem->getDelta().sync();
  
  return rNorm0;
}

Member Data Documentation

vector<shared_ptr<LinearSystem> > AMG::_coarseLinearSystems

private

Definition at line 87 of file AMG.h.

Referenced by cleanup(), createCoarseLevels(), cycle(), and doSweeps().

LinearSystem* AMG::_finestLinearSystem

private

Definition at line 86 of file AMG.h.

Referenced by cleanup(), createCoarseLevels(), cycle(), doSweeps(), smooth(), and solve().

bool AMG::_isCOMMWORLD

private

Definition at line 109 of file AMG.h.

Referenced by flipComm().

bool AMG::_isMerge

private

Definition at line 99 of file AMG.h.

Referenced by createCoarseLevels().

int AMG::_mergeLevel

private

Definition at line 98 of file AMG.h.

Referenced by createCoarseLevels(), and cycle().

int AMG::_mergeLevelSize

private

Definition at line 97 of file AMG.h.

Referenced by createCoarseLevels().

shared_ptr<LinearSystemMerger> AMG::_mergeLS

private

Definition at line 88 of file AMG.h.

Referenced by createCoarseLevels(), and cycle().

int AMG::_totalIterations

private

Definition at line 100 of file AMG.h.

Referenced by solve().

int AMG::amg_indx = 0

staticprivate

Definition at line 95 of file AMG.h.

int AMG::coarseGroupSize

Definition at line 77 of file AMG.h.

Referenced by createCoarseLevels().

CycleType AMG::cycleType

Definition at line 79 of file AMG.h.

Referenced by smooth(), and solve().

streambuf* AMG::m_backup

private

Definition at line 107 of file AMG.h.

Referenced by redirectPrintToFile(), and redirectPrintToScreen().

ofstream AMG::m_filestr

private

Definition at line 108 of file AMG.h.

Referenced by redirectPrintToFile(), and redirectPrintToScreen().

streambuf* AMG::m_psbuf

private

Definition at line 106 of file AMG.h.

Referenced by redirectPrintToFile().

int AMG::maxCoarseLevels

Definition at line 74 of file AMG.h.

Referenced by createCoarseLevels().

int AMG::nPostSweeps

Definition at line 76 of file AMG.h.

Referenced by cycle().

int AMG::nPreSweeps

Definition at line 75 of file AMG.h.

Referenced by cycle().

bool AMG::scaleCorrections

Definition at line 81 of file AMG.h.

Referenced by cycle().

SmootherType AMG::smootherType

Definition at line 80 of file AMG.h.

Referenced by doSweeps().

double AMG::weightRatioThreshold

Definition at line 78 of file AMG.h.

Referenced by createCoarseLevels().

---

The documentation for this class was generated from the following files:

• AMG.h
• AMG.cpp