anchor.diff:  
          enddo
   
  +       print *, 'i = ', i
  +       print *, 'r: ', r_xm, r_xp
  +       print *, 'u: ', u_xm, u_xp
  +       print *, 'p: ', p_xm, p_xp
  +
          
          ! density
          sum_xm = 0.0_dp_t
  
positive.code:        enddo
  
         Q_l%data(i+1,iqpres) = p_xp + sum_xp
         Q_l%data(i,iqpres) = p_xm + sum_xm
  
      enddo
  
      ! clean-up
  
negative.code:        enddo
  
         Q_l%data(i+1,iqdens) = r_xp + sum_xp
         Q_r%data(i,iqdens) = r_xm + sum_xm
  
  
         ! velocity
  