#include <stdlib.h>
#include <stdio.h>
#include <mpi.h>
#include <mpix.h>

// BLACS
#ifdef GPAW_NO_UNDERSCORE_CBLACS
#define Cblacs_gridexit_   Cblacs_gridexit
#define Cblacs_gridinit_   Cblacs_gridinit
#define Csys2blacs_handle_ Csys2blacs_handle
#define Cblacs2sys_handle_ Cblacs2sys_handle
#endif

void Cblacs_gridexit_(int ConTxt);

void Cblacs_gridinit_(int* ConTxt, char* order, int nprow, int npcol);

int Csys2blacs_handle_(MPI_Comm comm);

MPI_Comm Cblacs2sys_handle_(int ConTxt);

// End of BLACS  

int main(int argc, char *argv[])
{
  int nprow = 4;
  int npcol = 4;

  int iam, nprocs;
  int ConTxt;
  int result = 0;

  char order = 'R';

  // Create blacs grid on this communicator                                        
  MPI_Comm bg_comm;

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &iam);

  // Sanity check on MPI_COMM_WORLD, then reset result to zero.
  MPIX_Get_property(MPI_COMM_WORLD, MPIDO_RECT_COMM, &result);
  if(result) fprintf(stderr, "MPI_COMM_WORLD is a rectangular comm\n");
  result = 0;

  ConTxt = Csys2blacs_handle_(MPI_COMM_WORLD);
  Cblacs_gridinit_(&ConTxt, &order, nprow, npcol);

  if (ConTxt != -1) {
    bg_comm = Cblacs2sys_handle_(ConTxt);
    MPIX_Get_property(bg_comm, MPIDO_RECT_COMM, &result);
    if(result) fprintf(stderr, "bg_comm is a rectangular subcomm\n");
  }

  MPI_Barrier(MPI_COMM_WORLD);
  MPI_Finalize();
}