anchor.diff:         write(17, "(A, I0)") 'nProcY = ', nProcY
       end if
       call clean_stop(0, .FALSE.)
  -    stop 1
     end if
   
     ! myid starts at zero, so index these variables from zero.
  
positive.code:     if (minval(depth) .lt. 0) then
        write(17, "(A)") "Depths must be positive."
        call clean_stop(0, .FALSE.)
        stop 1
      end if
    end if
  
  
negative.code:         if (data(i,j,k) .ne. data(i,j,k)) then
            write(17, "(A, I0)") "NaN detected at time step ", n
            call clean_stop(n, .FALSE.)
          end if
        end do
      end do
  