'returns a tuple of (eigenvalues,eigenvectors) for the data set.'

def getEigensystem(self):

    if (self._eig is None):
        res = np.linalg.eig(self.getCovarianceMatrix())
        sorti = np.argsort(res[0])[::(-1)]
        res = (res[0][sorti], res[1][:, sorti])
        self._eig = res
    return self._eig
