def _poisson_log_likelihood(self, S, R):
        """
        Compute the log likelihood of a Poisson matrix with rates R

        :param S:   Count matrix
        :param R:   Rate matrix
        :return:    log likelihood
        """
        return (S * np.log(R) - R*self.dt).sum()
dataset/ETHPy150Open slinderman/pyhawkes/pyhawkes/models.py/_DiscreteTimeNetworkHawkesModelBase._poisson_log_likelihood/original