#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 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. Changing
the first line to
{{{
C_1 = self.connection_coefficients().copy()
}}}
also fixes the problem.
I have deleted the old version of the code and uploaded a new version of
the patch. Apart from a few changes here and there, I think the code is
in great shape! If I have time this week, I will work on writing some doc
tests for the new methods.
I noticed from the worksheet that your version of the code is in a .py
file in your home directory -- are you familiar with applying patches
through the hg version control system? I'm just asking since this would
be a good way of coordinating our work if we work on different areas in
the file.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10132#comment:19>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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