AMG.h

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// This file os part of FVM
// Copyright (c) 2012 FVM Authors
// See LICENSE file for terms.

#ifndef _AMG_H_
#define _AMG_H_

#include <vector>
#include <cmath>
#include "LinearSystem.h"
#include "LinearSolver.h"

#include "MultiFieldReduction.h"
#include "LinearSystemMerger.h"
#include <iostream>
#include <fstream>

class LinearSystemMerger;

using namespace std;

class AMG : public LinearSolver
{
public:

  enum CycleType
    {
      V_CYCLE,
      W_CYCLE,
      F_CYCLE
    };

  enum SmootherType
    {
      GAUSS_SEIDEL,
      JACOBI
    };
  
  AMG();
  virtual ~AMG();

  DEFINE_TYPENAME("AMG");
  
  virtual MFRPtr solve(LinearSystem & ls);
  virtual void smooth(LinearSystem & ls);


  virtual void setMergeLevelSize(int ls_size){ 
#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 redirectPrintToFile( const string& fname );
   void redirectPrintToScreen( );
   int getTotalIterations() const { return _totalIterations;}

   virtual void cleanup();
  
  // these parameters can be tuned.
  int maxCoarseLevels;
  int nPreSweeps;
  int nPostSweeps;
  int coarseGroupSize;
  double weightRatioThreshold;
  CycleType cycleType;
  SmootherType smootherType;
  bool scaleCorrections;
private:

  AMG(const AMG&);
  
  LinearSystem* _finestLinearSystem;
  vector<shared_ptr<LinearSystem> > _coarseLinearSystems;
  shared_ptr<LinearSystemMerger>   _mergeLS;

  void  createCoarseLevels( );
  void  doSweeps( const int nSweeps, const int level );
  void  cycle(  CycleType cycleType, const int level );
  void  flipComm();

  static int amg_indx;
 
  int _mergeLevelSize; //where 
  int _mergeLevel; 
  bool _isMerge;
  int _totalIterations;

#ifdef FVM_PARALLEL
  MPI::Intracomm _commTarget;
#endif

  streambuf *m_psbuf;
  streambuf *m_backup;
  ofstream m_filestr;
  bool _isCOMMWORLD;
};

#endif