#10132: Parametrization of (metric) surfaces in 3D euclidean space
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Reporter: mikarm | Owner:
mikarm
Type: enhancement | Status:
needs_review
Priority: major | Milestone:
sage-5.11
Component: geometry | Resolution:
Keywords: differential geometry, parametrized surface | Work issues:
Report Upstream: N/A | Reviewers:
vdelecroix
Authors: Mikhail Malakhaltsev, Joris Vankerschaver | Merged in:
Dependencies: #11549, #12737 | Stopgaps:
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Changes (by jvkersch):
* status: needs_work => needs_review
* dependencies: #11549 => #11549, #12737
Comment:
Hi Vincent, thanks again for your awesome comments. I have implemented all
of the changes you suggested, and I briefly describe the most significant
changes below.
Replying to [comment:68 vdelecroix]:
>
> 0) ... your file is still not linked in the reference manual, modify the
file 'doc/en/reference/geometry/index.rst' accordingly.
I haven't included the files in 'geometry/index.rst' as that file seems to
deal with combinatorial geometry mostly. Instead, I've linked from the
front page of the documentation, and I've put an entry under 'geometry and
topology'.
> 1) Many tests fail on my computer because of the random (?) order of
terms in a symbolic expression.
I think this is a consequence of some changes in the behavior of
multivariate symbolic expressions: I used to have no problems like this
for the 3 years that I've been testing this patch, but with a reasonably
recent version of Sage I see the same problems that you notice. I've
therefore taken the liberty of simply adapting the doctests, trusting that
the new ordering of the terms is the default behavior from now on.
> 6) I was not able to build a point in the parametrization.
I've added methods `point` and `tangent_vector`, which do what you
suggested. Adding these methods also had the advantage of making the
implementation somewhat clearer: I've now removed `eq_callable` (which was
not very clear to begin with) and replaced its invocation with calls to
the method `point()`.
>
> 7) Do you agree to add this example in the doc ?
This is a very nice and illustrative example; I've added it to the class
documentation.
Some other changes that I've made include anticipating #12737, which
removes `simplify_radical` from `simplify_full`. I found that we actually
rely on `simplify_radical` a lot, among other things to get rid of
expressions like `sqrt(x^2)/x' for `x > 0'. I've implemented a small
helper function to call both simplification methods successively. For the
rest, I've also made tons of little changes to the doctests.
Let me know if you need more information.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10132#comment:70>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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