void PETScVector::gatherLocalVectors( PetscScalar local_array[],
PetscScalar global_array[])
{
// Collect vectors from processors.
int size_rank;
MPI_Comm_size(PETSC_COMM_WORLD, &size_rank);
// number of elements to be sent for each rank
std::vector<PetscInt> i_cnt(size_rank);
MPI_Allgather(&_size_loc, 1, MPI_INT, &i_cnt[0], 1, MPI_INT, PETSC_COMM_WORLD);
// collect local array
PetscInt offset = 0;
// offset in the receive vector of the data from each rank
std::vector<PetscInt> i_disp(size_rank);
for(PetscInt i=0; i<size_rank; i++)
{
i_disp[i] = offset;
offset += i_cnt[i];
}
MPI_Allgatherv(local_array, _size_loc, MPI_DOUBLE,
global_array, &i_cnt[0], &i_disp[0], MPI_DOUBLE, PETSC_COMM_WORLD);
}
std::ostream &dump(std::ostream &os) const
{
std::size_t i_cnt(0);
for (std::size_t c(0); c < size(); ++c) {
std::size_t idx(std::get<0>(tup_items_alloc)[c * 2]);
std::size_t val(
std::get<0>(tup_items_alloc)[c * 2 + 1]
);
if ((c == idx) && (c == val)) {
++i_cnt;
continue;
}
if (i_cnt) {
os << "identity (" << i_cnt << " positions)\n";
i_cnt = 0;
}
os << c << ": " << idx << ", " << val << '\n';
}
if (i_cnt)
os << "identity (" << i_cnt << " positions)\n";
return os;
}