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Timeline for Residues of analytic operators

Current License: CC BY-SA 4.0

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Aug 13, 2023 at 9:01 comment added Jochen Glueck Sorry for being pedantic, but the edit still does not give the existence of the finite-rank map $P$, since $z \mapsto I - P_z$ could have an essential singularity at $z_0$. To get the map $P$ one also needs $I - P_{z_0}$ to be a Fredholm operator (or equivalently - as one has invertibility close to $z_0$ - a semi-Fredholm operator).
Aug 12, 2023 at 15:20 history edited M.González CC BY-SA 4.0
typo
Aug 12, 2023 at 13:34 history edited YCor
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Aug 12, 2023 at 12:02 comment added Igor Khavkine From the way the question is written, it is not so clear what you are after. According to the question, $h$ is arbitrary, so it is not clear what information it could give you about the residue. If all you know is the approximate value of $z_0$, then you could use any of the usual iterative eigenvalue/eigenvector approximation methods. Also, as noted in the other comment, perhaps you meant to write $z_0$ for the eigenvalue, or set $z_0=1$.
S Aug 12, 2023 at 11:41 history suggested CommunityBot CC BY-SA 4.0
the spetrum of $P_{z_0}$ possesses an isolated eigenvalue $1$ (assuming multiplicity is 1 and $I-P_z$ near $z_0$ is invertible).
Aug 11, 2023 at 19:49 review Suggested edits
S Aug 12, 2023 at 11:41
Aug 11, 2023 at 19:14 comment added Jochen Glueck There seem to be some assumptions missing. Under the given assumptions there doesn't need to exist such a projection $P$. In fact, $I-P_z$ need not even be invertible for $z$ close to $z_0$. (By the way, you probably want to replace $1$ with $\lambda$, but this doesn't fix the aforementioned issues.)
Aug 11, 2023 at 18:45 history edited LSpice CC BY-SA 4.0
Capitalise title
S Aug 11, 2023 at 18:24 review First questions
Aug 12, 2023 at 7:15
S Aug 11, 2023 at 18:24 history asked opera CC BY-SA 4.0