Neumann-series perturbation
= Neumann-series perturbation
If $A$ is invertible and $\|A^{-1}E\|<1$, then $A+E$ is invertible by the Neumann series. Similar iterative corrections prove stability of surjectivity.
= Neumann-series perturbation
If $A$ is invertible and $\|A^{-1}E\|<1$, then $A+E$ is invertible by the Neumann series. Similar iterative corrections prove stability of surjectivity.