def hessian(self, params):
        X = self.exog
        XB = np.dot(X,params)
        q = 2*self.endog - 1
        L = q*self.pdf(q*XB)/self.cdf(q*XB)
        return np.dot(-L*(L+XB)*X.T,X)
.. todo::
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/discrete/discrete_model.py/Probit.hessian--crossover with--dataset/ETHPy150Open lisa-lab/pylearn2/pylearn2/sandbox/cuda_convnet/probabilistic_max_pooling.py/ProbMaxPoolGrad._argument_contiguity_check