def get_rxn_params_dt(rxn, rev=False):
    """Write evaluation of the forward/reverse reaction rate constant

    Parameters
    ----------
    rxn : `ReacInfo`
        The reaction to consider
    rev : bool, optional
        If true, get the reverse constant rate constant derivative

    Returns
    -------
    jline : str
        String containing evaluation of forward/reverse reaction rate constant

    """
    jline = ''
    if rev:
        if abs(rxn.rev_par[1]) > 1e-90 and abs(rxn.rev_par[2]) > 1e-90:
            jline += '{:.16e} + '.format(rxn.rev_par[1]
                ) + '({:.16e} / T)'.format(rxn.rev_par[2])
        elif abs(rxn.rev_par[1]) > 1e-90:
            jline += '{:.16e}'.format(rxn.rev_par[1])
        elif abs(rxn.rev_par[2]) > 1e-90:
            jline += '({:.16e} / T)'.format(rxn.rev_par[2])
    elif abs(rxn.b) > 1e-90 and abs(rxn.E) > 1e-90:
        jline += '{:.16e} + ({:.16e} / T)'.format(rxn.b, rxn.E)
    elif abs(rxn.b) > 1e-90:
        jline += '{:.16e}'.format(rxn.b)
    elif abs(rxn.E) > 1e-90:
        jline += '({:.16e} / T)'.format(rxn.E)
    return jline
