code: def rate(totflux, pi, qminus):
      r
      return dense.tpt.rate(totflux, pi, qminus)
docs: r"""Transition rate for reaction A to B.
  
      Parameters
      ----------
      totflux : float
          The total flux between reactant and product
      pi : (M,) ndarray
          Stationary distribution
      qminus : (M,) ndarray
          Backward comittor
  
      Returns
      -------
      kAB : float
          The reaction rate (per time step of the
          Markov chain)
  
      See also
      --------
      committor, total_flux, flux_matrix
  
      Notes
      -----
      Computation of the rate relies on discrete transition path theory
      (TPT). The transition rate, i.e. the total number of reaction events per
      time step, is given in [1] as:
  
      .. math:: k_{AB}=\frac{1}{F} \sum_i \pi_i q_i^{(-)}
  
      :math:`F` is the total flux for the transition from :math:`A` to
      :math:`B`.
  
      References
      ----------
      .. [1] F. Noe, Ch. Schuette, E. Vanden-Eijnden, L. Reich and
          T. Weikl: Constructing the Full Ensemble of Folding Pathways
          from Short Off-Equilibrium Simulations.
          Proc. Natl. Acad. Sci. USA, 106, 19011-19016 (2009)