#10132: Differential Geometry via Sage
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Reporter: mikarm | Owner: mhampton
Type: enhancement | Status: new
Priority: major | Milestone:
Component: geometry | Keywords: differential geometry,
parametrized surface
Author: Mikhail Malakhaltsev | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by jason):
Replying to [comment:19 jvkersch]:
> Yes! You are quite right about the bug (which I must have introduced
while making the code into a patch the first time). I was worried about
the fact that parallel transport did not seem to preserve lengths, but
then I falsely convinced myself that was due to the fact that maybe the
curves used weren't parametrized by arc length. I'm quite glad to see
that this is solved now.
>
> The problem with the code that I wrote is the following: when writing
> {{{
> C_1 = self.connection_coefficients()
> for coef in C_1:
> C_1[coef] = C_1[coef].subs({u1: curve[0], u2: curve[1]})
> }}}
> `C_1` will just be a reference to the connection coefficients
dictionary, and not a genuine copy. So when we change it on the next
lines, we are in fact changing the global dictionary of connection
coefficients.
Are you sure? In the code (the latest patch), it appears that the
`connection_coefficients` return value is constructed as a new dictionary
each time the function is called.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10132#comment:20>
Sage <http://www.sagemath.org>
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