SetNumberOfVariables_LinearEuler2D_t Subroutine

  subroutine SetNumberOfVariables_LinearEuler2D_t(this)
    implicit none
    class(LinearEuler2D_t),intent(inout) :: this

    this%nvar = 5
    ! Only the first three variables (u, v, P) are advanced in time. The
    ! fourth and fifth variables, the sound speed c and background density rho0,
    ! are spatially-varying but time-constant background fields: their flux and
    ! source are identically zero, so they are excluded from time integration
    ! rather than stepped to a no-op.
    this%nstepped = 3

  endsubroutine SetNumberOfVariables_LinearEuler2D_t