subroutine is_mass_scan (iflag)
c
c------------------------------------------------------------------------------
c
c     iflag = 1 ==> in mass scan mode
c     iflag = 0 ==> not in mass scan mode
c------------------------------------------------------------------------------
c
      integer*4 irpa(32), jrpa(512), jmsh(512), nrpa, ndif_1, iflag

      common/rpamsh/jrpa,jmsh
c
c------------------------------------------------------------------------------
c------------------------------------------------------------------------------
c
      nrpa = 32
      call fndval (jrpa, nrpa, irpa, ndif_1)     ! get unique RPA values
      iflag = 0     ! initialize to not in mass scan mode
      if (ndif_1 .gt. 0) then
         call sort (irpa, ndif_1)
         num0 = 32
         do i = 1, 32
            if (irpa(i) .gt. 0) num0 = num0 - 1
         end do
         if (num0 .ge. 22) iflag = 1     ! not enough RPA values
      else     ! no RPA values, assume mass scan mode
         iflag = 1
      end if
c
c------------------------------------------------------------------------------
c------------------------------------------------------------------------------
c
      return
      end