anchor.diff:         ! velocity
          sum_xm = 0.0_dp_t
          sum_xp = 0.0_dp_t
  -       do n = 1, nprim
  +       do n = 1, nwaves
             sum_xm = sum_xm + beta_xm(n)*rvec(n,2)
             sum_xp = sum_xp + beta_xp(n)*rvec(n,2)
          enddo
  
positive.code: module interface_states_plm_module
  
    use datatypes_module
    use  grid_module
    use   variables_module
    use params_module
    use eos_module
  
    implicit none
  
  
negative.code: 
      dtdx = dt/U%grid%dx
  
      ! The basic idea here is that we do a characteristic
      ! decomposition.  The jump in primitive variables (Q) can be
      ! transformed to a jump in characteristic variables using the left
  