anchor.diff:         enddo
   
          Q_l%data(i+1,iqdens) = r_xp + sum_xp
  -       Q_l%data(i,iqdens) = r_xm + sum_xm
  +       Q_r%data(i,iqdens) = r_xm + sum_xm
   
   
          ! velocity
  
positive.code:        enddo
  
         Q_l%data(i+1,iqxvel) = u_xp + sum_xp
         Q_l%data(i,iqxvel) = u_xm + sum_xm
  
  
         ! pressure
  
negative.code: 
         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
  