PCTwoLevelsBlockDiagonal.cpp

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#include "PCTwoLevelsBlockDiagonal.hpp"
#include "Exception.hpp"

#include <iostream>

PCTwoLevelsBlockDiagonal::PCTwoLevelsBlockDiagonal(KSP& rKspObject, std::vector<PetscInt>& rBathNodes)
{
    PCTwoLevelsBlockDiagonalCreate(rKspObject, rBathNodes);
    PCTwoLevelsBlockDiagonalSetUp();
}

PCTwoLevelsBlockDiagonal::~PCTwoLevelsBlockDiagonal()
{
    PetscTools::Destroy(mPCContext.A11_matrix_subblock);
    PetscTools::Destroy(mPCContext.A22_B1_matrix_subblock);
    PetscTools::Destroy(mPCContext.A22_B2_matrix_subblock);

    PCDestroy(PETSC_DESTROY_PARAM(mPCContext.PC_amg_A11));
    PCDestroy(PETSC_DESTROY_PARAM(mPCContext.PC_amg_A22_B1));
    PCDestroy(PETSC_DESTROY_PARAM(mPCContext.PC_amg_A22_B2));

    PetscTools::Destroy(mPCContext.x1_subvector);
    PetscTools::Destroy(mPCContext.y1_subvector);

    PetscTools::Destroy(mPCContext.x21_subvector);
    PetscTools::Destroy(mPCContext.y21_subvector);

    PetscTools::Destroy(mPCContext.x22_subvector);
    PetscTools::Destroy(mPCContext.y22_subvector);

    VecScatterDestroy(PETSC_DESTROY_PARAM(mPCContext.A11_scatter_ctx));
    VecScatterDestroy(PETSC_DESTROY_PARAM(mPCContext.A22_B1_scatter_ctx));
    VecScatterDestroy(PETSC_DESTROY_PARAM(mPCContext.A22_B2_scatter_ctx));
}

void PCTwoLevelsBlockDiagonal::PCTwoLevelsBlockDiagonalCreate(KSP& rKspObject, std::vector<PetscInt>& rBathNodes)
{
    KSPGetPC(rKspObject, &mPetscPCObject);

    Mat system_matrix, dummy;
    MatStructure flag;
    KSPGetOperators(rKspObject, &system_matrix, &dummy, &flag);

    PetscInt num_rows, num_columns;
    MatGetSize(system_matrix, &num_rows, &num_columns);
    assert(num_rows==num_columns);

    PetscInt num_local_rows, num_local_columns;
    MatGetLocalSize(system_matrix, &num_local_rows, &num_local_columns);

    // Odd number of rows: impossible in Bidomain.
    // Odd number of local rows: impossible if V_m and phi_e for each node are stored in the same processor.
    if ((num_rows%2 != 0) || (num_local_rows%2 != 0))
    {
        TERMINATE("Wrong matrix parallel layout detected in PCLDUFactorisation.");
    }

    // Allocate memory
    unsigned subvector_num_rows = num_rows/2;
    unsigned subvector_local_rows = num_local_rows/2;

    unsigned subvector_num_rows_tissue = subvector_num_rows - rBathNodes.size();
    unsigned subvector_local_rows_tissue = subvector_num_rows_tissue; 

    unsigned subvector_num_rows_bath = rBathNodes.size();
    unsigned subvector_local_rows_bath = subvector_num_rows_bath; 

    assert(PetscTools::IsSequential());

    mPCContext.x1_subvector = PetscTools::CreateVec(subvector_num_rows, subvector_local_rows);
    mPCContext.x21_subvector = PetscTools::CreateVec(subvector_num_rows_tissue, subvector_local_rows_tissue);
    mPCContext.x22_subvector = PetscTools::CreateVec(subvector_num_rows_bath, subvector_local_rows_bath);
    mPCContext.y1_subvector = PetscTools::CreateVec(subvector_num_rows, subvector_local_rows);
    mPCContext.y21_subvector = PetscTools::CreateVec(subvector_num_rows_tissue, subvector_local_rows_tissue);
    mPCContext.y22_subvector = PetscTools::CreateVec(subvector_num_rows_bath, subvector_local_rows_bath);

    // Define IS objects that will be used throughout the method
    IS A11_all_rows;
    ISCreateStride(PETSC_COMM_WORLD, num_rows/2, 0, 2, &A11_all_rows);

    IS A22_all_rows;
    PetscInt A22_size;
    VecGetSize(mPCContext.x1_subvector, &A22_size);
    ISCreateStride(PETSC_COMM_WORLD, A22_size, 1, 2, &A22_all_rows);

    IS A22_bath_rows;
    PetscInt* phi_e_bath_rows = new PetscInt[rBathNodes.size()];
    for (unsigned index=0; index<rBathNodes.size(); index++)
    {
        phi_e_bath_rows[index] = 2*rBathNodes[index] + 1;
    }
#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 2) //PETSc 3.2 or later
    ISCreateGeneral(PETSC_COMM_WORLD, rBathNodes.size(), phi_e_bath_rows, PETSC_USE_POINTER, &A22_bath_rows);
 #else
    ISCreateGeneralWithArray(PETSC_COMM_WORLD, rBathNodes.size(), phi_e_bath_rows, &A22_bath_rows);
#endif

    IS A22_tissue_rows;
    ISDifference(A22_all_rows, A22_bath_rows, &A22_tissue_rows);

    // Create scatter contexts
    {
        // Needed by VecScatterCreate in order to find out parallel layout.
        Vec dummy_vec = PetscTools::CreateVec(num_rows, num_local_rows);

        IS& A11_rows=A11_all_rows;
        IS& A22_B1_rows=A22_tissue_rows;
        IS& A22_B2_rows=A22_bath_rows;

        IS all_vector;
        ISCreateStride(PETSC_COMM_WORLD, num_rows/2, 0, 1, &all_vector);

        IS tissue_vector;
        ISCreateStride(PETSC_COMM_WORLD, (num_rows/2)-rBathNodes.size(), 0, 1, &tissue_vector);

        IS bath_vector;
        ISCreateStride(PETSC_COMM_WORLD, rBathNodes.size(), 0, 1, &bath_vector);

        VecScatterCreate(dummy_vec, A11_rows, mPCContext.x1_subvector, all_vector, &mPCContext.A11_scatter_ctx);
        VecScatterCreate(dummy_vec, A22_B1_rows, mPCContext.x21_subvector, tissue_vector, &mPCContext.A22_B1_scatter_ctx);
        VecScatterCreate(dummy_vec, A22_B2_rows, mPCContext.x22_subvector, bath_vector, &mPCContext.A22_B2_scatter_ctx);

        ISDestroy(PETSC_DESTROY_PARAM(all_vector));
        ISDestroy(PETSC_DESTROY_PARAM(tissue_vector));
        ISDestroy(PETSC_DESTROY_PARAM(bath_vector));

        PetscTools::Destroy(dummy_vec);
    }

    // Get matrix sublock A11
    {
        // Work out local row range for subblock A11 (same as x1 or y1)
        PetscInt low, high, global_size;
        VecGetOwnershipRange(mPCContext.x1_subvector, &low, &high);
        VecGetSize(mPCContext.x1_subvector, &global_size);
        assert(global_size == num_rows/2);

        IS A11_local_rows;
        IS& A11_columns=A11_all_rows;
        ISCreateStride(PETSC_COMM_WORLD, high-low, 2*low, 2, &A11_local_rows); 

#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 1) //PETSc 3.1 or later
        MatGetSubMatrix(system_matrix, A11_local_rows, A11_columns,
            MAT_INITIAL_MATRIX, &mPCContext.A11_matrix_subblock);
#else
        MatGetSubMatrix(system_matrix, A11_local_rows, A11_columns, PETSC_DECIDE,
            MAT_INITIAL_MATRIX, &mPCContext.A11_matrix_subblock);
#endif

        ISDestroy(PETSC_DESTROY_PARAM(A11_local_rows));
    }

    // Get matrix sublock A22_B1
    {
//        // Work out local row range for subblock A22 (same as x2 or y2)
//        PetscInt low, high, global_size;
//        VecGetOwnershipRange(mPCContext.x21_subvector, &low, &high);
//        VecGetSize(mPCContext.x21_subvector, &global_size);
//        assert(global_size == (num_rows/2) - (PetscInt) rBathNodes.size());

        assert(PetscTools::IsSequential());
        IS& A22_B1_local_rows = A22_tissue_rows; // wrong in parallel, need to give local rows
        IS& A22_B1_columns = A22_tissue_rows;

#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 1) //PETSc 3.1 or later
        MatGetSubMatrix(system_matrix, A22_B1_local_rows, A22_B1_columns,
            MAT_INITIAL_MATRIX, &mPCContext.A22_B1_matrix_subblock);
#else
        MatGetSubMatrix(system_matrix, A22_B1_local_rows, A22_B1_columns, PETSC_DECIDE,
            MAT_INITIAL_MATRIX, &mPCContext.A22_B1_matrix_subblock);
#endif

    }

    // Get matrix sublock A22_B2
    {
//        // Work out local row range for subblock A22 (same as x2 or y2)
//        PetscInt low, high, global_size;
//        VecGetOwnershipRange(mPCContext.x21_subvector, &low, &high);
//        VecGetSize(mPCContext.x21_subvector, &global_size);
//        assert(global_size == (num_rows/2) - (PetscInt) rBathNodes.size());

        assert(PetscTools::IsSequential());
        IS& A22_B2_local_rows = A22_bath_rows; // wrong in parallel, need to give local rows
        IS& A22_B2_columns = A22_bath_rows;

#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 1) //PETSc 3.1 or later
        MatGetSubMatrix(system_matrix, A22_B2_local_rows, A22_B2_columns,
            MAT_INITIAL_MATRIX, &mPCContext.A22_B2_matrix_subblock);
#else
        MatGetSubMatrix(system_matrix, A22_B2_local_rows, A22_B2_columns, PETSC_DECIDE,
            MAT_INITIAL_MATRIX, &mPCContext.A22_B2_matrix_subblock);
#endif
    }

    ISDestroy(PETSC_DESTROY_PARAM(A11_all_rows));
    ISDestroy(PETSC_DESTROY_PARAM(A22_all_rows));
    ISDestroy(PETSC_DESTROY_PARAM(A22_bath_rows));
    delete[] phi_e_bath_rows;
    ISDestroy(PETSC_DESTROY_PARAM(A22_tissue_rows));

    // Register call-back function and its context
    PCSetType(mPetscPCObject, PCSHELL);
#if (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 2) //PETSc 2.2
    PCShellSetApply(mPetscPCObject, PCTwoLevelsBlockDiagonalApply, (void*) &mPCContext);
#else
    // Register PC context so it gets passed to PCTwoLevelsBlockDiagonalApply
    PCShellSetContext(mPetscPCObject, &mPCContext);

    // Register call-back function
    PCShellSetApply(mPetscPCObject, PCTwoLevelsBlockDiagonalApply);
#endif
}

void PCTwoLevelsBlockDiagonal::PCTwoLevelsBlockDiagonalSetUp()
{
    // These options will get read by PCSetFromOptions
    PetscOptionsSetValue("-pc_hypre_boomeramg_max_iter", "1");
    PetscOptionsSetValue("-pc_hypre_boomeramg_strong_threshold", "0.0");
    PetscOptionsSetValue("-pc_hypre_type", "boomeramg");

    // Set up amg preconditioner for block A11
    PCCreate(PETSC_COMM_WORLD, &(mPCContext.PC_amg_A11));
    PCSetType(mPCContext.PC_amg_A11, PCBJACOBI);
    PCSetOperators(mPCContext.PC_amg_A11, mPCContext.A11_matrix_subblock, mPCContext.A11_matrix_subblock, DIFFERENT_NONZERO_PATTERN);//   SAME_PRECONDITIONER);
    PCSetFromOptions(mPCContext.PC_amg_A11);
    PCSetUp(mPCContext.PC_amg_A11);

    // Set up amg preconditioner for block A22_B1
    PCCreate(PETSC_COMM_WORLD, &(mPCContext.PC_amg_A22_B1));
    PCSetType(mPCContext.PC_amg_A22_B1, PCBJACOBI);
    PCSetOperators(mPCContext.PC_amg_A22_B1, mPCContext.A22_B1_matrix_subblock, mPCContext.A22_B1_matrix_subblock, DIFFERENT_NONZERO_PATTERN);//   SAME_PRECONDITIONER);
    PCSetFromOptions(mPCContext.PC_amg_A22_B1);
    PCSetUp(mPCContext.PC_amg_A22_B1);

    // Set up amg preconditioner for block A22_B2
    PCCreate(PETSC_COMM_WORLD, &(mPCContext.PC_amg_A22_B2));
    PCSetType(mPCContext.PC_amg_A22_B2, PCHYPRE);
    //PCHYPRESetType(mPCContext.PC_amg_A22_B2, "boomeramg");
    PetscOptionsSetValue("-pc_hypre_type", "boomeramg");

    PetscOptionsSetValue("-pc_hypre_boomeramg_max_iter", "1");
    PetscOptionsSetValue("-pc_hypre_boomeramg_strong_threshold", "0.0");
    PetscOptionsSetValue("-pc_hypre_boomeramg_coarsen_type", "HMIS");

    PCSetOperators(mPCContext.PC_amg_A22_B2, mPCContext.A22_B2_matrix_subblock, mPCContext.A22_B2_matrix_subblock, DIFFERENT_NONZERO_PATTERN);//   SAME_PRECONDITIONER);
    PCSetFromOptions(mPCContext.PC_amg_A22_B2);
    PCSetUp(mPCContext.PC_amg_A22_B2);
}

#if (PETSC_VERSION_MAJOR == 3 && PETSC_VERSION_MINOR >= 1) //PETSc 3.1 or later
PetscErrorCode PCTwoLevelsBlockDiagonalApply(PC pc_object, Vec x, Vec y)
{
  void* pc_context;

  PCShellGetContext(pc_object, &pc_context);
#else
PetscErrorCode PCTwoLevelsBlockDiagonalApply(void* pc_context, Vec x, Vec y)
{
#endif

    // Cast the context pointer to PCTwoLevelsBlockDiagonalContext
    PCTwoLevelsBlockDiagonal::PCTwoLevelsBlockDiagonalContext* block_diag_context = (PCTwoLevelsBlockDiagonal::PCTwoLevelsBlockDiagonalContext*) pc_context;
    assert(block_diag_context!=NULL);

    /*
     * Scatter x = [x1 x21 x22]'
     */
//PETSc-3.x.x or PETSc-2.3.3
#if ( (PETSC_VERSION_MAJOR == 3) || (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 3 && PETSC_VERSION_SUBMINOR == 3)) //2.3.3 or 3.x.x
    VecScatterBegin(block_diag_context->A11_scatter_ctx, x, block_diag_context->x1_subvector, INSERT_VALUES, SCATTER_FORWARD);
    VecScatterEnd(block_diag_context->A11_scatter_ctx, x, block_diag_context->x1_subvector, INSERT_VALUES, SCATTER_FORWARD);
#else
    VecScatterBegin(x, block_diag_context->x1_subvector, INSERT_VALUES, SCATTER_FORWARD, block_diag_context->A11_scatter_ctx);
    VecScatterEnd(x, block_diag_context->x1_subvector, INSERT_VALUES, SCATTER_FORWARD, block_diag_context->A11_scatter_ctx);
#endif

//PETSc-3.x.x or PETSc-2.3.3
#if ( (PETSC_VERSION_MAJOR == 3) || (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 3 && PETSC_VERSION_SUBMINOR == 3)) //2.3.3 or 3.x.x
    VecScatterBegin(block_diag_context->A22_B1_scatter_ctx, x, block_diag_context->x21_subvector, INSERT_VALUES, SCATTER_FORWARD);
    VecScatterEnd(block_diag_context->A22_B1_scatter_ctx, x, block_diag_context->x21_subvector, INSERT_VALUES, SCATTER_FORWARD);
#else
    VecScatterBegin(x, block_diag_context->x21_subvector, INSERT_VALUES, SCATTER_FORWARD, block_diag_context->A22_B1_scatter_ctx);
    VecScatterEnd(x, block_diag_context->x21_subvector, INSERT_VALUES, SCATTER_FORWARD, block_diag_context->A22_B1_scatter_ctx);
#endif

//PETSc-3.x.x or PETSc-2.3.3
#if ( (PETSC_VERSION_MAJOR == 3) || (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 3 && PETSC_VERSION_SUBMINOR == 3)) //2.3.3 or 3.x.x
    VecScatterBegin(block_diag_context->A22_B2_scatter_ctx, x, block_diag_context->x22_subvector, INSERT_VALUES, SCATTER_FORWARD);
    VecScatterEnd(block_diag_context->A22_B2_scatter_ctx, x, block_diag_context->x22_subvector, INSERT_VALUES, SCATTER_FORWARD);
#else
    VecScatterBegin(x, block_diag_context->x22_subvector, INSERT_VALUES, SCATTER_FORWARD, block_diag_context->A22_B2_scatter_ctx);
    VecScatterEnd(x, block_diag_context->x22_subvector, INSERT_VALUES, SCATTER_FORWARD, block_diag_context->A22_B2_scatter_ctx);
#endif

    /*
     * y1  = ILU(A11)*x1
     * y21 = ILU(A22)*x21
     * y22 = AMG(A22)*x22
     */
    PCApply(block_diag_context->PC_amg_A11, block_diag_context->x1_subvector, block_diag_context->y1_subvector);
    PCApply(block_diag_context->PC_amg_A22_B1, block_diag_context->x21_subvector, block_diag_context->y21_subvector);
    PCApply(block_diag_context->PC_amg_A22_B2, block_diag_context->x22_subvector, block_diag_context->y22_subvector);

    /*
     * Gather y = [y1 y21 y22]'
     */
//PETSc-3.x.x or PETSc-2.3.3
#if ( (PETSC_VERSION_MAJOR == 3) || (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 3 && PETSC_VERSION_SUBMINOR == 3)) //2.3.3 or 3.x.x
    VecScatterBegin(block_diag_context->A11_scatter_ctx, block_diag_context->y1_subvector, y, INSERT_VALUES, SCATTER_REVERSE);
    VecScatterEnd(block_diag_context->A11_scatter_ctx, block_diag_context->y1_subvector, y, INSERT_VALUES, SCATTER_REVERSE);
#else
    VecScatterBegin(block_diag_context->y1_subvector, y, INSERT_VALUES, SCATTER_REVERSE, block_diag_context->A11_scatter_ctx);
    VecScatterEnd(block_diag_context->y1_subvector, y, INSERT_VALUES, SCATTER_REVERSE, block_diag_context->A11_scatter_ctx);
#endif

//PETSc-3.x.x or PETSc-2.3.3
#if ( (PETSC_VERSION_MAJOR == 3) || (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 3 && PETSC_VERSION_SUBMINOR == 3)) //2.3.3 or 3.x.x
    VecScatterBegin(block_diag_context->A22_B1_scatter_ctx, block_diag_context->y21_subvector, y, INSERT_VALUES, SCATTER_REVERSE);
    VecScatterEnd(block_diag_context->A22_B1_scatter_ctx, block_diag_context->y21_subvector, y, INSERT_VALUES, SCATTER_REVERSE);
#else
    VecScatterBegin(block_diag_context->y21_subvector, y, INSERT_VALUES, SCATTER_REVERSE, block_diag_context->A22_B1_scatter_ctx);
    VecScatterEnd(block_diag_context->y21_subvector, y, INSERT_VALUES, SCATTER_REVERSE, block_diag_context->A22_B1_scatter_ctx);
#endif

//PETSc-3.x.x or PETSc-2.3.3
#if ( (PETSC_VERSION_MAJOR == 3) || (PETSC_VERSION_MAJOR == 2 && PETSC_VERSION_MINOR == 3 && PETSC_VERSION_SUBMINOR == 3)) //2.3.3 or 3.x.x
    VecScatterBegin(block_diag_context->A22_B2_scatter_ctx, block_diag_context->y22_subvector, y, INSERT_VALUES, SCATTER_REVERSE);
    VecScatterEnd(block_diag_context->A22_B2_scatter_ctx, block_diag_context->y22_subvector, y, INSERT_VALUES, SCATTER_REVERSE);
#else
    VecScatterBegin(block_diag_context->y22_subvector, y, INSERT_VALUES, SCATTER_REVERSE, block_diag_context->A22_B2_scatter_ctx);
    VecScatterEnd(block_diag_context->y22_subvector, y, INSERT_VALUES, SCATTER_REVERSE, block_diag_context->A22_B2_scatter_ctx);
#endif

    return 0;
}