#9650: Adding support for differential forms
-----------------------------------+----------------------------------------
Reporter: jvkersch | Owner: burcin
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.5.3
Component: symbolics | Keywords: forms, functions, symbolics
Author: Joris Vankerschaver | Upstream: N/A
Reviewer: Niles Johnson | Merged:
Work_issues: diff() |
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Changes (by niles):
* status: needs_review => needs_work
* work_issues: documentation formatting, duplicates in
coordinate_patch.py => diff()
Comment:
I agree; documentation builds cleanly, looks good, and the code works
nicely. As Joris has said, this is intentionally a very basic
implementation; I think later patches should add functionality and
flexibility (e.g. differential forms over other rings, and coercion
between forms over different sets of variables, as is done for
multivariate polynomial rings)
Replying to [comment:27 mhampton]:
> This looks good to me too, although I'm not sure if this is desired
behavior:
>
{{{
U = CoordinatePatch((x,y))
F2 = DifferentialForms(U)
q = DifferentialForm(F2,1)
q[0] = -y
q[1] = x
diff(q,y)
}}}
> gives
>
{{{
0
}}}
> but it seems like diff(q,y) should give dx/\dy. I'm pretty rusty with
my differntial forms though, I'll try to brush up.
>
This problem is caused because `diff()` first tries to call
`q.differentiate()` and, failing that, coerces `q` to the symbolic ring
and differentiates it there. Adding a `differentiate()` method which
simply calls `q.diff()` would solve this problem. Depending on what you
think is best, you could silently ignore additional arguments to `diff`,
or you could throw an error if additional arguments are present.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9650#comment:28>
Sage <http://www.sagemath.org>
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