PCG (Preconditioned Conjugate Gradient) methods are more effective than CG (Conjugate Gradient) methods to solve optimization problems (in machine learning).
So my question is how can I find that if a dataset is ill-conditioned?
Condition number (l) = max value of eigen value divided by min value of eigen value.
If l >> 1 then it we say it is ill-conditioned
If l approx = 1 the well-conditioned.