#12255: coeffs() fails on symbolic functions
-------------------------+--------------------------------------------------
Reporter: mjo | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: symbolics | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Description changed by mjo:
Old description:
> 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 worked in 4.7,
>
> {{{
> sage: f.coeffs(g)
> [[g(t)^2 + t + 3*g(t), 0]]
> }}}
New description:
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]]
}}}
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12255#comment:1>
Sage <http://www.sagemath.org>
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