parameter( Nx=50, Ny=16 )
      parameter( Lx=Nx+2, Ly=Ny+2 )
      parameter( gamma_gas=1.4 )

      real M_inlet, Nx_inv, Ny_inv, NxNy_inv

      common/constants/ pi, c0, c0_inv, p_fac, p_fac_inv

      common/mesh/ grid(Lx+1,Ly+1,2), cent(Lx,Ly,2), 
     &             sx(Lx+1,Ly+1,2), ds_x_inv(Lx+1,Ly+1),
     &             sy(Lx+1,Ly+1,2), ds_y_inv(Lx+1,Ly+1),
     &             vol(Lx,Ly), vol_inv(Lx,Ly), 
     &             Nx_inv, Ny_inv, NxNy_inv

      common/tstep/ time, dt, cfl, gamma(4), zeta(4), beta(4),
     &              nrk_max, nt

      common/operation/ M_inlet, p_ratio, p_exit

      common/solver/ eps_diss, i_scheme