Calculates the pdf of a lognormal distribution with parameters mean
        and sigma

        Parameters
        ----------
        mean : float or ndarray
            Mean of the lognormal distribution
        sigma : float or ndarray
            Sigma parameter of the lognormal distribution

        Returns
        -------
        : float or ndarray
            pdf of x

def _pdf_w_mean(self, x, mean, sigma):
        """
        Calculates the pdf of a lognormal distribution with parameters mean
        and sigma

        Parameters
        ----------
        mean : float or ndarray
            Mean of the lognormal distribution
        sigma : float or ndarray
            Sigma parameter of the lognormal distribution

        Returns
        -------
        : float or ndarray
            pdf of x
        """

        # Lognorm pmf with mean for optimization
        mu, sigma = self.translate_args(mean, sigma)
        return self.logpdf(x, mu, sigma)