In the above figures, the quantity 'pinv' refers to the `numpy.linalg.pinv` function. The figures indicate that the inner product using the right-hand inverse matrix is consistent with the left-hand inverse matrix, and also the off-diagonal elements are nearly equal to zero. Therefore, `pinv` more robust.
Now, we discuss that the covariance matrix is ill-conditioned (i.e. almost singular).
Now, we discuss that the covariance matrix is ill-conditioned (i.e., nearly singular).