def inverse(self, z):
    '\n        Inverse of the negative binomial transform\n\n        Parameters\n        ----------\n        z : array_like\n            The value of the inverse of the negative binomial link at `p`.\n\n        Returns\n        -------\n        p : ndarray\n            Mean parameters\n\n        Notes\n        -----\n        g^(-1)(z) = exp(z)/(alpha*(1-exp(z)))\n        '
    return ((- 1) / (self.alpha * (1 - np.exp((- z)))))
Inverse of the negative binomial transform

Parameters
----------
z : array_like
    The value of the inverse of the negative binomial link at `p`.

Returns
-------
p : ndarray
    Mean parameters

Notes
-----
g^(-1)(z) = exp(z)/(alpha*(1-exp(z)))
def inverse(self, z):
    '\n        Inverse of the negative binomial transform\n\n        Parameters\n        ----------\n        z : array_like\n            The value of the inverse of the negative binomial link at `p`.\n\n        Returns\n        -------\n        p : ndarray\n            Mean parameters\n\n        Notes\n        -----\n        g^(-1)(z) = exp(z)/(alpha*(1-exp(z)))\n        '
    return ((- 1) / (self.alpha * (1 - np.exp((- z)))))