On 28.03.2012 17:06, krastanov.ste...@gmail.com wrote:
(1) I think it would be good to extend the "usage" section to give some
    non-trivial examples. It does not matter if you make the particulars
    of input/output forms up, just show what you envision your code
    should be able to do at the end of the summer, in a best-case
    scenario.
I will extend that part.

Great. Let us know of changes.


(2) Add details on how you plan to implement things. What new classes
    will here be, what data structures do they hold? E.g. a manifold is
    typicaly constructed from patching open subsets of R^n along
    diffeomorphisms - but I am not aware of sympy code to represent even
    open balls (I could be wrong, obviously).
OK.


(3) Are there any non-trivial algorithms that you think could be
    implemented? (For example, might it be feasible to compute the
    euler characteristic of a Manifold via the Hopf index theorem?)

Most of the paper that I referred to is about working independently of
coordinates, then at the end choosing a coordinate system and deriving
something useful in that system (differential equation about
something, finding an integral, a pullback, a connection).

That sounds very sensible. I would love to e.g. put a symbolic metric on a manifold and get out symbolically the Christoffel symbols.

When those
are found, it is the rest of sympy that comes into play. For example
in the case of Hoph theorem, it would be easy to get equations for the
vector field, check them for zeros, get the maps around those zeroes
and then rely on something in sympy to find the index of those maps.
However, this is the naive algorithm which assumes perfect solvers and
so on, so probably it won't work.

Sure, I was just fantasizing ;).


So, about data structures and algorithms: nothing nontrivial, it will
depend on what is already in sympy. I will add examples of interesting
results possible with this project.


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