//preceding code

int M = 12;
for (int i = 0; i < L; i++) //START OF PARALLEL CHUNK
{
    funkystuffresults = dosomefunkystuff();

    for (int j = 0; j < M; j++)
    {
        resultmatrix[i*M + j] = funkystuffresults
    }
}//END OF PARALLEL CHUNK

MPI_Comm_size(MPI_COMM_WORLD, &world_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
    int sendcounts[world_size];
    int displs[world_size];
    vector<int> rec_buf(L);
    int rem = L%world_size;
    int counttester = 0;
    for (int i = 0; i < world_size; i++)
    {
        sendcounts[i] = L/world_size;
        if (rem > 0)
        {
            sendcounts[i]++;
            rem--;
        }
        displs[i] = counttester;
        counttester += sendcounts[i];
    }
    vector<int> paralleli(L);
    for (int i = 0; i < L; i++)
    {
        paralleli[i] = i;
    }
    MPI_Scatterv(&paralleli, sendcounts, displs, MPI_INT, &rec_buf, L, MPI_INT, 0, MPI_COMM_WORLD);
    for (int i = 0; i < L; i++) //START OF PARALLEL CHUNK
    {
         //previously mentioned code
    }