Residue incorrect for extensions of CA and FM extensions

[saraedum]

This has been reported on sage-devel recently:

sage: K = ZpCA(3,5)
sage: R.<a> = K[]
sage: L.<a> = K.extension(a^2 - 3)
sage: a.residue()
1

CC: @roed314 @xcaruso

Component: padics

Author: Julian Rüth

Branch: 5917d5d

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/25879

[saraedum]

comment:2

The issue seems to be in expansion(n):

sage: a.expansion()
[0, 1]
sage: a.expansion(0)
1

The problem is a line that says:

return ulist[n - self.ordp]

Here the index is negative in our case (n=0, self.ordp=1)

[saraedum]

Branch: u/saraedum/25879

[saraedum]

New commits:

ff8e3f4

Port expansion fix from CR to CA and FM

[saraedum]

Author: Julian Rüth

[saraedum]

Commit: ff8e3f4

[sagetrac-git]

Changed commit from ff8e3f4 to 5917d5d

[sagetrac-git]

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

5917d5d

Port expansion fix from CR to CA and FM

[saraedum]

New commits:

5917d5d

Port expansion fix from CR to CA and FM

[saraedum]

Work Issues: is the patchbot happy?

[fchapoton]

Reviewer: Frédéric Chapoton

[fchapoton]

comment:7

let it be

[saraedum]

Changed work issues from is the patchbot happy? to none

[vbraun]

Changed branch from u/saraedum/25879 to 5917d5d

[fchapoton]

Changed commit from 5917d5d to none