source: CIVL/examples/mpi-omp/AMG2013/parcsr_ls/par_coarse_parms.c

/*BHEADER**********************************************************************
 * Copyright (c) 2008,  Lawrence Livermore National Security, LLC.
 * Produced at the Lawrence Livermore National Laboratory.
 * This file is part of HYPRE.  See file COPYRIGHT for details.
 *
 * HYPRE is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License (as published by the Free
 * Software Foundation) version 2.1 dated February 1999.
 *
 * $Revision: 2.4 $
 ***********************************************************************EHEADER*/



/******************************************************************************
 *
 *****************************************************************************/

/* following should be in a header file */


#include "headers.h"



/*==========================================================================*/
/*==========================================================================*/
/**
  Generates global coarse_size and dof_func for next coarser level

  Notes:
  \begin{itemize}
  \item The routine returns the following:
  \begin{itemize}
  \item an integer array containing the
  function values for the local coarse points
  \item the global number of coarse points
  \end{itemize}
  \end{itemize}

  {\bf Input files:}
  headers.h

  @return Error code.
  
  @param comm [IN]
  MPI Communicator
  @param local_num_variables [IN]
  number of points on local processor
  @param dof_func [IN]
  array that contains the function numbers for all local points
  @param CF_marker [IN]
  marker array for coarse points 
  @param coarse_dof_func_ptr [OUT]
  pointer to array which contains the function numbers for local coarse points
  @param coarse_pnts_global_ptr [OUT]
  pointer to array which contains the number of the first coarse point on each  processor and the total number of coarse points in its last element
  
  @see */
/*--------------------------------------------------------------------------*/

int
hypre_BoomerAMGCoarseParms(MPI_Comm comm,
                           int      local_num_variables,
                           int      num_functions,
                           int     *dof_func,
                           int     *CF_marker, 
                           int    **coarse_dof_func_ptr, 
                           HYPRE_BigInt    **coarse_pnts_global_ptr) 
{
   int            i, lcs=0;
   int            ierr = 0;
   int            num_procs;
   HYPRE_BigInt   local_coarse_size = 0;

   int   *coarse_dof_func;
   HYPRE_BigInt  *coarse_pnts_global;

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

   MPI_Comm_size(comm,&num_procs);

   for (i=0; i < local_num_variables; i++)
   {
      if (CF_marker[i] == 1) lcs++;
   }
   if (num_functions > 1)
   {
      coarse_dof_func = hypre_CTAlloc(int,lcs);

      local_coarse_size = 0;
      for (i=0; i < local_num_variables; i++)
      {
         if (CF_marker[i] == 1)
            coarse_dof_func[lcs++] = dof_func[i];
      }
      *coarse_dof_func_ptr    = coarse_dof_func;
   }

   local_coarse_size = (HYPRE_BigInt) lcs; 
#ifdef HYPRE_NO_GLOBAL_PARTITION
   {
      HYPRE_BigInt scan_recv;
      
      coarse_pnts_global = hypre_CTAlloc(HYPRE_BigInt,2);
      MPI_Scan(&local_coarse_size, &scan_recv, 1, MPI_HYPRE_BIG_INT, MPI_SUM, comm);
      /* first point in my range */ 
      coarse_pnts_global[0] = scan_recv - local_coarse_size;
      /* first point in next proc's range */
      coarse_pnts_global[1] = scan_recv;

   }
      

#else
   coarse_pnts_global = hypre_CTAlloc(HYPRE_BigInt,num_procs+1);

   MPI_Allgather(&local_coarse_size,1,MPI_HYPRE_BIG_INT,&coarse_pnts_global[1],
                1,MPI_HYPRE_BIG_INT,comm);

   for (i=2; i < num_procs+1; i++)
      coarse_pnts_global[i] += coarse_pnts_global[i-1];
#endif




   *coarse_pnts_global_ptr = coarse_pnts_global;

   return (ierr);
}