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3 votes
3 answers
363 views

Why $\|(A + cI)^{-1}x\|\leq \frac{\|x\|}{\lambda_{\min}(A)}$

Given $A\succ 0$ (positive-definite) and $c>0$, I am trying to show $$\|(A + cI)^{-1}x\|\leq \frac{\|x\|}{\lambda_{\min}(A)} \tag{1}$$ using information like this but without success so far. Could ...
Thoth's user avatar
  • 865
4 votes
0 answers
379 views

Need to improve upper bound for $\| (uv^T + B)^{-1} \|$ (Sherman-Morrison formula)

I have a matrix $A \in \mathbb{C}^{n \times n}$ in the form $A = uv^T + B$, where $u,v \in \mathbb{C}^n$ and $B \in \mathbb{C}^{n \times n}$. I know $A$ is invertible and want to find an upper bound ...
Integral's user avatar
  • 6,574