The above plot shows the array of the eigenvalues. This plot indicates that the covariance matrix is ill-conditioned since several eigenvalues are close to zero. Also, the eigenvalues are oscillating around and after the index number 400 (the eigenvalues below ~1e-11), which occurs due to the numerical inaccuracies. This can affect the inverse calculation since the inverse is proportional to $`1/det(\Siagma)`$
However, the question is that why `pinv` is working better than the simple `inv` function.
However, the question is that why `pinv` is working better than the simple `inv` function.