def _cov_eigen(self, X):
        raise NotImplementedError('Not implemented in _PCABase. Use a ' +
                                  'subclass (and implement it there).')
Compute and return eigen{values,vectors} of X's covariance matrix.
dataset/ETHPy150Open lisa-lab/pylearn2/pylearn2/models/pca.py/_PCABase._cov_eigen