/* comm.c: Communication routines 
 * 
 * Madhu Nayakkankuppam, 10/09/2002
 *
 * Exchange of ghost cells for the Poisson problem and 1-D Jacobi sweep.
 *
 */

#ifndef _MPI_H
#include "mpi.h"
#endif

#ifndef _COMM_H
#include "comm.h"
#endif

/*--------------------------------------------------------------------------*/

void jacobi(double **a,         /* current solution matrix */ 
            double **b,         /* updated solution matrix */
            double **f,         /* right hand side */
            double h,           /* mesh spacing */
            int my_rank,        /* process rank */
            int p,              /* number of processes */
            int nx,             /* # grid points along x */
            int local_nx,       /* # grid points along y */
            int ptop,           /* process rank for next (above) row */
            int pbot,           /* process rank for preceding (below) row */
            int mode,           /* mode of communication */
            MPI_Comm *grid,     /* communicator */
            MPI_Request *a_req, /* array of 4 requests */
            MPI_Request *b_req, /* array of 4 requests */
            MPI_Status *status  /* array of 8 statuses */
            ) {

  /* Actual data is in a[1:local_nx][0:nx-1].  Boundary
     conditions apply to a[1][0:nx-1], a[local_nx][0:nx-1]
     for procs 0 and p-1, so 2 <= i <= local_nx-1 below.
     Likewise, boundary conditions apply to
     a[1:local_nx][0] and a[1:local_nx][nx-1], so 1 <= j
     <= nx-2 below for all procs.  
  */


}