SetNumberOfVariables_LinearEuler3D_t Subroutine

  subroutine SetNumberOfVariables_LinearEuler3D_t(this)
    implicit none
    class(LinearEuler3D_t),intent(inout) :: this

    this%nvar = 6
    ! Only the first four variables (u, v, w, P) are advanced in time. The
    ! fifth and sixth 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 = 4

  endsubroutine SetNumberOfVariables_LinearEuler3D_t