def METHOD_NAME(self, t=-1, fromt=0):
    r"""
    Evaluates the maximum attainable runaway momentum (in normalized units)
    at time ``t``. This momentum is obtained by integrating the equation of
    motion:
    .. math::
        \frac{\mathrm{d}p}{\mathrm{d}t} = eE \quad\implies\quad
        p = \int_0^t eE(t)\,\mathrm{d}t',
    where :math:`e` is the elementary charge and :math:`p` is the electron
    momentum.
    :param int t: Index of time to calculate transferred momentum until.
    """
    if np.isscalar(t):
        p = np.trapz(self[fromt:t], self.grid.t[fromt:t], axis=0)
    else:
        p = []
        t = np.asarray(t)
        if t.ndim != 1:
            raise OutputException("Unrecognized dimensions of time index: {}.".format(t.ndim))
        for time in t:
            p.append(np.trapz(self[fromt:time], self.grid.t[fromt:time], axis=0))
        p = np.array(p)
    p *= scipy.constants.e / (scipy.constants.m_e * scipy.constants.c)
    return p