anchor.diff:      !
       !       / u   r   0   \  
       !   A = | 0   u   1/r |  
  -    !       \ 0  rc^2 u  /
  +    !       \ 0  rc^2 u   /
       !
       ! With the rows corresponding to rho, u, and p
       !
  
positive.code:     enddo
  
  
  
      !-------------------------------------------------------------------------
      ! compute left and right primitive variable states
      !-------------------------------------------------------------------------
  
negative.code:           enddo
         enddo
  
         ! finally, sum up all the jumps
  
         ! density
         Q_l%data(i+1,iqdens) = 0.0_dp_t
  