bug with cyclotomic fields embeddings and coercions

[videlec]

sage: K60.<zeta60> = CyclotomicField(60)
sage: K30.<zeta30> = CyclotomicField(30, embedding=zeta60**2)
sage: K15.<zeta15> = CyclotomicField(15, embedding=zeta30**2)
sage: K5.<zeta5> = CyclotomicField(5, embedding=zeta15**3)
sage: zeta5 * zeta60
# BOOM #

see: https://groups.google.com/forum/#!topic/sage-support/J4rLkHUNU1E

CC: @JohnCremona

Component: number fields

Author: Vincent Delecroix

Branch/Commit: 1b5051f

Reviewer: Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/20513

[videlec]

New commits:

8d8602f	Trac 20400: conversion rational in NF -> QQbar
c96139a	Trac 20513: fix cyclotomic field embeddings

[videlec]

Branch: u/vdelecroix/20513

[videlec]

Commit: c96139a

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

7ccc962

Trac 20513: doctest

[sagetrac-git]

Changed commit from c96139a to 7ccc962

[sagetrac-git]

Changed commit from 7ccc962 to 1b5051f

[sagetrac-git]

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

6992729	Trac 20513: fix cyclotomic field embeddings
1b5051f	Trac 20513: doctest

[JohnCremona]

comment:4

The code looks good. I am building the branch to test now.

[kedlaya]

comment:5

Maybe add the example from #20261 as another doctest?

[videlec]

comment:6

#20261 is not fixed by this ticket.

[vbraun]

Reviewer: Volker Braun

[videlec]

comment:8

Thanks Volker!

[vbraun]

Changed branch from u/vdelecroix/20513 to 1b5051f