SUBROUTINE GSUM_R8( ans, phi )

#ifdef ALLOW_MPI
#include "mpif.h"
#endif

      Real*8 ans
      Real*8 phi

      INTEGER RC

      ans = phi

#ifdef USE_MPI_GSUM
      CALL MPI_Allreduce( phi,
     &                    ans,
     &                      1,
     &                    MPI_REAL8,
     &                    MPI_SUM,
     &                    MPI_COMM_WORLD,
     &                    rc
     &                  )
#endif

#ifdef USE_JAM_GSUM
C     JAM global sum
      CALL JAM_barrier_start( phi )
      CALL JAM_barrier_done(  ans )
#endif

C     WRITE(6,*) ' phi = ', phi, ' Sum = ', ans
C     CALL MPI_Finalize( rc )
C     STOP

      RETURN
      END