linearmodels.system.gmm.HomoskedasticWeightMatrix.sigma¶ HomoskedasticWeightMatrix.sigma(eps, x)[source]¶ Estimate residual covariance. Parameters epsndarrayThe residuals from the system of equations. xlist[ndarray]A list of the regressor matrices for each equation in the system. Returns ndarrayThe estimated covariance matrix of the residuals. Return type ndarray