Residues in SymbolicRing

[dkrenn]

Calculate the residue of a symbolic expression.

Component: symbolics

Author: Daniel Krenn

Branch/Commit: 511b9ff

Reviewer: Marc Mezzarobba

Issue created by migration from https://trac.sagemath.org/ticket/15840

[dkrenn]

Branch: u/dkrenn/ticket/15840

[dkrenn]

New commits:

0467df4	First version of aau_howto
8931dbd	Workflow begonnen
e0d1169	function 'residue' added

[dkrenn]

Commit: e0d1169

[dkrenn]

Author: Daniel Krenn

[dkrenn]

comment:5

Having some git troubles....solving them tomorrow... ;)

[sagetrac-git]

Changed commit from e0d1169 to ddca280

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

ddca280

function 'residue' added

[dkrenn]

comment:7

Now the correct things are pushed :)

[mezzarobba]

comment:8

Hi Daniel,

Thanks for your patch!

Your code didn't work on expressions such as 1/s² (with that particular variable name). I think I fixed it.

I am still not too happy about the following:

sage: var('s')
sage: (x^s).residue(x,0)
0

but it's not clear to me what the code should do in such cases.

Also, I wonder if we shouldn't prefer a syntax such as expr.residue(x==a) for consistency with series().

---

New commits:

9997eaa

Various improvements to expr.residue()

[mezzarobba]

Changed branch from u/dkrenn/ticket/15840 to u/mmezzarobba/15840-residue

[mezzarobba]

Changed commit from ddca280 to 9997eaa

[mezzarobba]

Reviewer: Marc Mezzarobba

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

ae62eca

Various improvements to expr.residue()

[sagetrac-git]

Changed commit from 9997eaa to ae62eca

[dkrenn]

Changed branch from u/mmezzarobba/15840-residue to u/dkrenn/ticket/15840

[dkrenn]

Changed commit from ae62eca to 511b9ff

[dkrenn]

comment:11

Replying to @mezzarobba:

Also, I wonder if we shouldn't prefer a syntax such as expr.residue(x==a) for consistency with series().

Yes, good idea. I changed that.

---

New commits:

511b9ff

changed to support x==a syntax for consistency with .series()

[dkrenn]

comment:12

Replying to @mezzarobba:

I am still not too happy about the following:

sage: var('s')
sage: (x^s).residue(x,0)
0

but it's not clear to me what the code should do in such cases.

It is also not clear to me, but this problem has to be solved in {.series()}}}. This is now #15854.

[dkrenn]

comment:13

Replying to @mezzarobba:

Your code didn't work on expressions such as 1/s² (with that particular variable name). I think I fixed it.

Thanks. I reviewed your changes; looks good.

[vbraun]

Changed branch from u/dkrenn/ticket/15840 to 511b9ff