C CLUSTERCOLORF.F  (2006-08-22)
C RETRIEVES #CLUSTERS AND #PROCS IN EACH CLUSTER.

      PROGRAM MAIN
      IMPLICIT NONE
      INCLUDE 'MPIF.H'
      INTEGER SELF, IERR
      INTEGER NNODES(32)
      INTEGER NCLUSTERS

      CALL MPI_INIT(IERR)
      CALL MPI_COMM_RANK(MPI_COMM_WORLD, SELF, IERR)

      CALL GETNNODES(NNODES, NCLUSTERS)

      IF (SELF .EQ. 0) THEN
         PRINT *, 'NCLUSTERS=', NCLUSTERS
         PRINT *, 'NNODES=', NNODES
      END IF

      CALL MPI_FINALIZE(IERR)
      END

      SUBROUTINE GETNNODES(NNODES, NCLUSTERS)
      IMPLICIT NONE
      INCLUDE 'MPIF.H'
      INTEGER NNODES(32)
      INTEGER NCLUSTERS
      INTEGER COLOR, ATTR, IERR, I
      LOGICAL FLAG
      CALL MPI_ATTR_GET(MPI_COMM_WORLD, IMPI_CLIENT_SIZE,
     &		NCLUSTERS, FLAG, IERR)
      IF (.NOT. FLAG) THEN
        PRINT *, 'MPI_ATTR_GET FAILED'
        CALL EXIT(1)
      END IF
      CALL MPI_ATTR_GET(MPI_COMM_WORLD, IMPI_CLIENT_COLOR,
     &		COLOR, FLAG, IERR)
      IF (.NOT. FLAG) THEN
        PRINT *, 'MPI_ATTR_GET FAILED'
        CALL EXIT(1)
      END IF

      DO I = 1, 32
         NNODES(I) = 0
      END DO
      NNODES(COLOR + 1) = 1
      CALL MPI_ALLREDUCE(MPI_IN_PLACE, NNODES, NCLUSTERS,
     &		MPI_INTEGER, MPI_SUM, MPI_COMM_WORLD, IERR)

      RETURN
      END