coeffs() fails on symbolic functions

[orlitzky]

This was reported on sage-support:

http://groups.google.com/group/sage-support/t/fa439b8dd28daaa8

As of 4.8.alpha6,

sage: g = function('g', var('t'))
sage: f = 3*g + g**2 + t
sage: f.coeffs(g)
...
ValueError: The name "g(t)" is not a valid Python identifier.

This didn't throw a ValueError in 4.7,

sage: f.coeffs(g)
[[g(t)^2 + t + 3*g(t), 0]]

but the result was still not the expected one. The correct answer would be,

sage: f.coeffs(g)
[[t, 0],[3, 1], [1, 2]]

Component: symbolics

Author: Michael Orlitzky

Branch/Commit: 3c181a0

Reviewer: Ralf Stephan

Issue created by migration from https://trac.sagemath.org/ticket/12255

[rwst]

comment:6

This seems fixed now (still wasn't in 6.2):

/home/ralf/sage/src/bin/sage-ipython:1: DeprecationWarning: coeffs is deprecated. Please use coefficients instead.
See http://trac.sagemath.org/17438 for details.
  #!/usr/bin/env python
[[t, 0], [3, 1], [1, 2]]

[orlitzky]

Commit: 3c181a0

[orlitzky]

Branch: u/mjo/ticket/12255

[orlitzky]

comment:7

Indeed, but let's add a doctest to Expression.coefficients() if you don't mind.

---

New commits:

3c181a0

Trac #12255: Add a doctest for the fixed behavior.

[orlitzky]

Author: Michael Orlitzky

[rwst]

comment:8

Is fine!

[rwst]

Reviewer: Ralf Stephan

[vbraun]

Changed branch from u/mjo/ticket/12255 to 3c181a0