PetscSolverPfc.cc 6.32 KB
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/******************************************************************************
 *
 * Extension of AMDiS - Adaptive multidimensional simulations
 *
 * Copyright (C) 2013 Dresden University of Technology. All Rights Reserved.
 * Web: https://fusionforge.zih.tu-dresden.de/projects/amdis
 *
 * Authors: Simon Praetorius et al.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *
 * See also license.opensource.txt in the distribution.
 * 
 ******************************************************************************/

#include "PetscSolverPfc.h"
#include "parallel/PetscHelper.h"
#include "parallel/PetscSolverGlobalMatrix.h"

namespace AMDiS { namespace Parallel {

  using namespace std;
  
  /// solve Pfc Preconditioner
  PetscErrorCode pcPfcShell(PC pc, Vec b, Vec x) // solve Px=b
  { FUNCNAME("pcPfcShell()");
  
    void *ctx;
    PCShellGetContext(pc, &ctx);
    PfcData* data = static_cast<PfcData*>(ctx);
    
    Vec b1, b2, b3, x1, x2, x3;
    VecNestGetSubVec(b, 0, &b1);
    VecNestGetSubVec(b, 1, &b2);
    VecNestGetSubVec(b, 2, &b3);

    VecNestGetSubVec(x, 0, &x1);
    VecNestGetSubVec(x, 1, &x2);
    VecNestGetSubVec(x, 2, &x3);


    // Hilfsvariablen
    Vec y1, y2, tmp;
    VecDuplicate(b1, &y1);
    VecDuplicate(b1, &y2);
    VecDuplicate(b1, &tmp);

    KSPSolve(data->kspM, b1, y1); 			// M*y1 = b1    
    MatMult(data->matK, y1, tmp); 			// tmp := K*y1
    VecAYPX(tmp, -(data->tau), b2);			// tmp := b2 - tau*tmp
    
    KSPSolve(data->kspMpK, tmp, y2); 			// (M+sqrt(tau)K)*y2 = tmp
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    MatMult(data->matM, y2, tmp);			// tmp := M*y2
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    KSPSolve(data->kspMpK2, tmp, x2); 			// MpK2*x2 = tmp
    MatMult(data->matM, x2, tmp);			// tmp := M*x2
    KSPSolve(data->kspMpK2, tmp, x2); 			// MpK2*x2 = tmp
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    VecCopy(x2, x1); 					// x1 := x2
    VecAXPBYPCZ(x1, 1.0, 1.0/(data->delta), -1.0/(data->delta), y1, y2);	// x1 = 1*y1 + factor*y2 - factor*x1

    MatMult(data->matK, x2, tmp); 			// tmp := K*x2
    VecAYPX(tmp, -1.0, b3);				// tmp := b3 - tmp
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    KSPSolve(data->kspM, tmp, x3); 			// M*x3 = tmp    
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    VecDestroy(&y1);
    VecDestroy(&y2);
    VecDestroy(&tmp);
    
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    return 0;
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  }
  
  void PetscSolverPfc::initSolver(KSP &ksp)
  {
    // Create FGMRES based outer solver
    KSPCreate(meshDistributor->getMpiComm(0), &ksp);
    KSPSetOperators(ksp, getMatInterior(), getMatInterior(), SAME_NONZERO_PATTERN);
    if (getInfo() >= 10)
      KSPMonitorSet(ksp, KSPMonitorDefault, PETSC_NULL, PETSC_NULL);
    else if (getInfo() >= 20)
      KSPMonitorSet(ksp, KSPMonitorTrueResidualNorm, PETSC_NULL, PETSC_NULL);
    petsc_helper::setSolver(ksp, "pfc_", KSPFGMRES, PCNONE, getRelative(), getTolerance(), getMaxIterations());
    KSPSetFromOptions(ksp);
    
    
    if (useOldInitialGuess)
      KSPSetInitialGuessNonzero(ksp, PETSC_TRUE);
  }
  

  void PetscSolverPfc::initPreconditioner(PC pc)
  {
    FUNCNAME("PetscSolverPfc::initPreconditioner()");

    TEST_EXIT(tau)("tau pointer not set!\n");
    
    PCSetType(getPc(), PCSHELL);
    PCShellSetApply(getPc(), pcPfcShell);
    PCShellSetContext(getPc(), &data);
    
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    double delta = sqrt(*tau);
    double eps = sqrt(0.5);
    
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    const FiniteElemSpace *feSpace = componentSpaces[0];
    
    // create mass-matrix
    DOFMatrix matrixM(feSpace, feSpace);
    Operator massOp(feSpace, feSpace);
    Simple_ZOT zot;
    massOp.addTerm(&zot);
    matrixM.assembleOperator(massOp);
    
    solverM = createSubSolver(0, "M_");
    solverM->fillPetscMatrix(&matrixM);
    data.matM = solverM->getMatInterior();
    data.kspM = solverM->getSolver();
    
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    // create MpK-matrix
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    DOFMatrix matrixMpK(feSpace, feSpace);
    Operator laplaceOp2(feSpace, feSpace);
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    Simple_SOT sot2(delta);
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    laplaceOp2.addTerm(&zot);
    laplaceOp2.addTerm(&sot2);
    matrixMpK.assembleOperator(laplaceOp2);
    
    solverMpK = createSubSolver(0, "MpK_");
    solverMpK->fillPetscMatrix(&matrixMpK);
    matMpK = solverMpK->getMatInterior();
    data.kspMpK = solverMpK->getSolver();
    
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    // create MpK2-matrix
    DOFMatrix matrixMpK2(feSpace, feSpace);
    Operator laplaceOp3(feSpace, feSpace);
    Simple_SOT sot3(eps*sqrt(delta));
    laplaceOp3.addTerm(&zot);
    laplaceOp3.addTerm(&sot3);
    matrixMpK2.assembleOperator(laplaceOp3);
    
    solverMpK2 = createSubSolver(0, "MpK2_");
    solverMpK2->fillPetscMatrix(&matrixMpK2);
    matMpK2 = solverMpK2->getMatInterior();
    data.kspMpK2 = solverMpK2->getSolver();
    
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    // create laplace-matrix
    DOFMatrix matrixK(feSpace, feSpace);
    Operator laplaceOp(feSpace, feSpace);
    Simple_SOT sot;
    laplaceOp.addTerm(&sot);
    matrixK.assembleOperator(laplaceOp);
    
    solverK = createSubSolver(0, "K_");
    solverK->fillPetscMatrix(&matrixK);
    data.matK = solverK->getMatInterior();
    
    // === Setup preconditioner data ===    
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    data.delta = delta;
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    data.tau = (*tau);

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    petsc_helper::setSolver(data.kspM, "M_", KSPCG, PCBJACOBI, 0.0, 1e-8, 5);
    petsc_helper::setSolver(data.kspMpK, "MpK_", KSPCG, PCBJACOBI, 0.0, 1e-6, 20);
    petsc_helper::setSolver(data.kspMpK2, "MpK2_", KSPCG, PCBJACOBI, 0.0, 1e-6, 10);
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  }


  void PetscSolverPfc::exitPreconditioner(PC pc)
  {
    FUNCNAME("PetscSolverPfc::exit()");
    
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//     MatDestroy(&matMpK);
//     MatDestroy(&matMpK2);
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    solverM->destroyMatrixData();
    solverK->destroyMatrixData();
    solverMpK->destroyMatrixData();
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    solverMpK2->destroyMatrixData();
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    solverM->destroyVectorData();
    solverK->destroyVectorData();
    solverMpK->destroyVectorData();
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    solverMpK2->destroyVectorData();
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    delete solverM;
    solverM = NULL;
    delete solverK;
    solverK = NULL;
    delete solverMpK;
    solverMpK = NULL;
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    delete solverMpK2;
    solverMpK2 = NULL;
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  }
  
  
  PetscSolver* PetscSolverPfc::createSubSolver(int component,
					      string kspPrefix)
  {
    FUNCNAME("PetscSolverPfc::createSubSolver()");
    
    vector<const FiniteElemSpace*> fe;
    fe.push_back(componentSpaces[component]);
    
    PetscSolver* subSolver = new PetscSolverGlobalMatrix("");
    subSolver->setKspPrefix(kspPrefix.c_str());
    subSolver->setMeshDistributor(meshDistributor, 0);
    subSolver->init(fe, fe);
    
    ParallelDofMapping &subDofMap = subSolver->getDofMap();
    subDofMap[0] = dofMap[component];
    subDofMap.update();
    
    return subSolver;
  }
} }