constructor Function

  pure function constructor(ref_rho, ref_t, ref_s, beta_t, beta_s) result(this)
    real(r8), intent(in) :: ref_rho
      !! The density for the temperature and salinity about which the
      !! equation of state was linearised, \(\rho_0\).
    real(r8), intent(in) :: ref_t
      !! The temperature about which the equation of state was
      !! linearised, \(T_0\).
    real(r8), intent(in) :: ref_s
      !! The salinity about which the equation of state was
      !! linearised, \(S_0\).
    real(r8), intent(in) :: beta_t
      !! The thermal contraction coefficient, \(\beta_T\).
    real(r8), intent(in) :: beta_s
      !! The haline contraction coefficient, \(\beta_S\).
    type(linear_eos)     :: this
    this%ref_rho = ref_rho
    this%ref_t   = ref_t
    this%ref_s   = ref_s
    this%beta_t  = beta_t
    this%beta_s  = beta_s
  end function constructor