PetscVecTools.hpp

/*

Copyright (C) University of Oxford, 2005-2011

University of Oxford means the Chancellor, Masters and Scholars of the
University of Oxford, having an administrative office at Wellington
Square, Oxford OX1 2JD, UK.

This file is part of Chaste.

Chaste is free software: you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation, either version 2.1 of the License, or
(at your option) any later version.

Chaste is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details. The offer of Chaste under the terms of the
License is subject to the License being interpreted in accordance with
English Law and subject to any action against the University of Oxford
being under the jurisdiction of the English Courts.

You should have received a copy of the GNU Lesser General Public License
along with Chaste. If not, see <http://www.gnu.org/licenses/>.

*/


#ifndef _PETSCVECTOOLS_HPP_
#define _PETSCVECTOOLS_HPP_

#include "UblasVectorInclude.hpp" // needs to be 'first'

#include <petscvec.h>

class PetscVecTools
{
public:
    static void Assemble(Vec vector);

    static void Display(Vec vector);

    static void Zero(Vec vector);

    static void SetElement(Vec vector, PetscInt row, double value);

    static void AddToElement(Vec vector, PetscInt row, double value);

    static unsigned GetSize(Vec vector);

    static void GetOwnershipRange(Vec vector, PetscInt& lo, PetscInt& hi);

    static double GetElement(Vec vector, PetscInt row);
    
    static void AddScaledVector(Vec y, Vec x, double scaleFactor);

    static void Scale(Vec vector, double scaleFactor);
    
    static void WAXPY(Vec w, double a, Vec x, Vec y);


    template<size_t VECTOR_SIZE>
    static void AddMultipleValues(Vec vector, unsigned* vectorIndices, c_vector<double, VECTOR_SIZE>& smallVector)
    {
        PetscInt indices_owned[VECTOR_SIZE];
        PetscInt num_indices_owned = 0;
        PetscInt global_row;
        PetscInt lo, hi;
        GetOwnershipRange(vector, lo, hi);

        for (unsigned row = 0; row<VECTOR_SIZE; row++)
        {
            global_row = vectorIndices[row];
            if (global_row >=lo && global_row <hi)
            {
                indices_owned[num_indices_owned++] = global_row;
            }
        }

        if (num_indices_owned == VECTOR_SIZE)
        {
            VecSetValues(vector,
                         num_indices_owned,
                         indices_owned,
                         smallVector.data(),
                         ADD_VALUES);
        }
        else
        {
            // We need continuous data, if some of the rows do not belong to the processor their values
            // are not passed to VecSetValues
            double values[VECTOR_SIZE];
            unsigned num_values_owned = 0;

            for (unsigned row = 0; row<VECTOR_SIZE; row++)
            {
                global_row = vectorIndices[row];
                if (global_row >= lo && global_row < hi)
                {
                    values[num_values_owned++] = smallVector(row);
                }
            }

            VecSetValues(vector,
                         num_indices_owned,
                         indices_owned,
                         values,
                         ADD_VALUES);
        }
    }

    static void SetupInterleavedVectorScatterGather(Vec interleavedVec, VecScatter& rFirstVariableScatterContext, VecScatter& rSecondVariableScatterContext);


    static void DoInterleavedVecScatter(Vec interleavedVec, VecScatter firstVariableScatterContext, Vec firstVariableVec, VecScatter secondVariableScatterContext, Vec secondVariableVec);

    static void DoInterleavedVecGather(Vec interleavedVec, VecScatter firstVariableScatterContext, Vec firstVariableVec, VecScatter secondVariableScatterContext, Vec secondVariableVec);

};

#endif //_PETSCVECTOOLS_HPP_

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