Hello, a couple of things struck me when I was looking at the mail regarding a proposed group theory project by Vamsi.
a) The manifolds in rn.py just need to setup a coordinate system, since the parameterisation is the identity map. How would one describe, say, Sn? Wouldn't Patch require an additional attribute which maps the coordinate system to the actual surface? In the same vein, if one defines patches, should there not be a way to check that the resulting patchwork is indeed a manifold, i.e, that continuity is satisfied? b) can we simply do plot(manifold) to visualise it? Since this seems to be of a more elementary nature as compared to the LieGroup thing, I think it will be a good exercise to write sn.py in the nature of rn.py which implements S1 and S2. It should also help me get a better hang of the code. I would also not mind doing the plot(manifold) functionality if it does not exist. Look forward to any pointers! Joy On Sun, Dec 28, 2014 at 4:26 AM, Joy merwin monteiro <[email protected]> wrote: > Thanks, Francesco. I have a little familiarity with Scheme, mainly due to > my > many attempts to read SICM. Thanks for that link, have mailed the author > of that > blog. > > You might have also come across https://github.com/davidsd/lie > Having a look at this as well, hopefully something will click! > > Thanks, > Joy > > > On Sat, Dec 27, 2014 at 10:29 PM, Francesco Bonazzi < > [email protected]> wrote: > >> *sympy.diffgeom* has been inspired by this source: >> >> http://groups.csail.mit.edu/mac/users/gjs/6946/calculus-indexed.pdf >> >> The code in that PDF is written in Scheme (a Lisp dialect). I don't know >> whether you have experience with that programming language, but it's quite >> hard to read. The module *sympy.diffgeom* can be thought of a kind of >> translation of the Scheme code into object-oriented Python code. >> >> Apparently someone already thought of extending the Scheme code to deal >> with Lie groups, and did it: >> http://wmfarr.blogspot.it/2006/06/functional-differential-geometry-in.html >> >> I have no idea about this work, anyways. The link to that blogger's code >> extension looks to be broken. >> >> >> On Saturday, December 27, 2014 12:28:21 PM UTC+1, Joy merwin monteiro >> wrote: >>> >>> Hello, >>> >>> I have been looking at the sympy code for a bit, especially the diffgeom >>> module. >>> It seems quite comprehensive, and was wondering if there has been >>> thinking >>> along the lines of creating a Lie Group class which subclasses from >>> Manifold and Group (? can't >>> find an abstract class of this type). One could then create various >>> instances of it, add >>> a coordinate system and a Lie Algebra to it for computations (analogous >>> to what is done in diffgeom.rn). >>> >>> My motivation for asking this is that Lie group based algorithms are >>> present in the ode module >>> and some code is also present in the liealgebra module (though it does >>> not seem to have an >>> algorithmic focus), and I felt it would tie things up nicely in terms >>> of structure. Symmetry methods for differential equations also >>> conceptualise the DE as a manifold itself, unless I'm mistaken. >>> In the (distant!) future I would like to contribute some algorithms for >>> symmetry methods in PDEs, >>> (which is why I looked at Sympy in the first place), but thought this >>> would be something more feasible and >>> will also allow me to familiarise myself with the sympy codebase. >>> >>> Look forward to any opinions/suggestions with regards to the feasibility >>> of something like this. Belated >>> Xmas wishes to all! >>> >>> TIA, >>> Joy >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/sympy. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/bb8833fa-0877-433a-ab7f-e935f0e5fdaf%40googlegroups.com >> <https://groups.google.com/d/msgid/sympy/bb8833fa-0877-433a-ab7f-e935f0e5fdaf%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > The best ruler, when he finishes his > tasks and completes his affairs, > the people say > “It all happened naturally” > > - Te Tao Ch'ing > -- The best ruler, when he finishes his tasks and completes his affairs, the people say “It all happened naturally” - Te Tao Ch'ing -- You received this message because you are subscribed to the Google Groups "sympy" group. 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