Derivations for rational function fields

[saraedum]

This adds derivations for function fields. It also implements a generator of the space of derivations for a rational function field.

Depends on #16521

Component: commutative algebra

Keywords: sd59

Author: Julian Rueth

Branch/Commit: 74468b4

Reviewer: Miguel Marco

Issue created by migration from https://trac.sagemath.org/ticket/16518

[saraedum]

Branch: u/saraedum/ticket/16518

[saraedum]

Dependencies: #16521

[sagetrac-git]

Commit: be532e5

[sagetrac-git]

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

dc81be8	Derivations for rational function fields
547f8da	is_perfect() for fields
be532e5	Added copyright header to finite_field_base.pyx

[miguelmarco]

Reviewer: Miguel Marco

[vbraun]

comment:6

Doc build

OSError: [function_] /home/release/Sage/local/lib/python2.7/site-packages/sage/rings/function_field/function_field.py:docstring of sage.rings.function_field.function_field:5: WARNING: Bullet list ends without a blank line; unexpected unindent.

[sagetrac-jkeitel]

Changed branch from u/saraedum/ticket/16518 to u/jkeitel/16518

[sagetrac-jkeitel]

comment:7

I've fixed the problem with the documentation, so I'm putting this back to positive review.

---

New commits:

6d2bf40	Merge branch 'master' into u/saraedum/ticket/16518
74468b4	Fixed docstring formatting.

[sagetrac-jkeitel]

Changed commit from be532e5 to 74468b4

[vbraun]

Changed branch from u/jkeitel/16518 to 74468b4