p2lol

void Vector_sum(double x[], double y[], double z[], int n)
{
  int elemsPerProc = n / comm_sz;
  int extraElems = n % comm_sz;

  //create recv buffers
  double* recvbuffx = (double *) malloc(sizeof(double) * (elemsPerProc + extraElems));
  double* recvbuffy = (double *) malloc(sizeof(double) * (elemsPerProc + extraElems));

  //create sendcounts array
  int sendcounts[] = malloc(sizeof(int) * comm_sz);
  int mallocCtr = 0;
  for(mallocCtr; mallocCtr < comm_sz; mallocCtr++)
  {
    //add extra elems to main process
    if(mallocCtr == 0)
    {
      sendcounts[mallocCtr] = elemsPerProc + extraElems;
    }
    else
    {
      sendcounts[mallocCtr] = elemsPerProc;
    }
  }

  //root scatters elements
  if(myid == 0)
  {
    MPI_Scatterv{x, sendcounts, sendcounts, MPI_Double, recvbuffx, elemsPerProc + extraElems,
      MPI_Double, 0, MPI_COMM_WORLD};
    MPI_Scatterv{y, sendcounts, sendcounts, MPI_Double, recvbuffy, elemsPerProc + extraElems,
      MPI_Double, 0, MPI_COMM_WORLD};
  }
}