SparsityPattern.h

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <vector>
 
#ifdef USE_PETSC
#include <petscsystypes.h>
#endif
 
namespace MathLib
{
template <typename IndexType>
struct SerialSparsityPattern
{
    std::vector<IndexType> number_non_zeros_per_row;

    IndexType nnzInRow(IndexType const row) const
    {
        return number_non_zeros_per_row[row];
    }

    IndexType numberOfRows() const
    {
        return static_cast<IndexType>(number_non_zeros_per_row.size());
    }
};
 
#ifdef USE_PETSC
struct PETScSparsityPattern
{
    std::vector<PetscInt> row_ptr;
    std::vector<PetscInt> col_idx;

    PetscInt nnzInRow(PetscInt const row) const
    {
        return row_ptr[row + 1] - row_ptr[row];
    }

    PetscInt numberOfRows() const
    {
        // A default-constructed pattern has an empty row_ptr and describes
        // zero rows; only a populated pattern carries the trailing sentinel.
        return row_ptr.empty() ? 0 : static_cast<PetscInt>(row_ptr.size()) - 1;
    }
};
#endif
}  // namespace MathLib