# Tag Info

You might want to use the fact that: $$||A||_2=\sigma_\max(A)$$ where $\sigma_\max$ is the largest singular value. If you are interested in details, this Math SO question should be interesting. Thus, $$||A^{-1}||_2=\frac{1}{\sigma_\min(A)}$$ where $\sigma_\min$ is the smallest singular value. You certainly want to avoid the actual calculation of the ...