The proposal still needs quite a bit of work.  I suspect that that's the
bigger deadline.  Do we accept PRs after the initial GSoC submission
deadline?


On Thu, Mar 20, 2014 at 3:18 PM, Ondřej Čertík <[email protected]>wrote:

> On Thu, Mar 20, 2014 at 1:40 PM, Peter Petrov <[email protected]>
> wrote:
> > Thanks for all the replies. This was so fast. You guys are great. I will
> > look into the references pointed out by Ondřej and try to narrow down a
> > concrete problem. What Matthew said is exactly my idea. Working on a
> physics
> > related problem will keep me interested and motivated to keep going, but
> I
> > will be thinking of implementing constructs in a general way to be used
> in
> > other problems. I think I will either focus on something tensor related
> > (Gamma matrices or some type of functionality which automatically
> > manipulates indices in different group representations), or maybe go with
> > the Feynman diagram suggestion of Ondřej. As Stefan pointed out The
> Feynman
> > diagram visualization is not really generalizable, but is still very
> > important for a big community. There might be some general topology
> > constructs there as well.
> >
> > Right now I started working on an issue to try and fix before the
> deadline.
> > I am looking at https://github.com/sympy/sympy/issues/7134. There have
> been
> > no replies for some months. Should I just post my thought in that thread
> and
> > see if anyone jumps in. I think I have an idea of a basic (probably not
> very
> > good, but hopefully working) resolution. At this point I am just trying
> to
> > have something to submit as a pull request, but I am a little stuck on
> some
> > technical details. I know its a simple issue, but I have to start
> somewhere
> > right.
>
> If you want to quickly start with something, pick some issue here:
>
>
> https://github.com/sympy/sympy/issues?labels=Easy+to+Fix&milestone=&page=1&state=open
>
> Ondrej
>
> >
> > Thanks again for all the comments!
> >
> >
> > On Thursday, March 20, 2014 2:34:24 PM UTC-4, Matthew wrote:
> >>
> >> My thoughts on what's written so far are different from Ondrej's.  I am
> >> less excited by physics applications and more excited by the tools
> necessary
> >> to enable the expression of physics applications.  The extent to which a
> >> domain specific project like this can be broken into a generally
> applicable
> >> component (some mathy or algorithmic bit) and a domain specific
> application
> >> (some physics thing) is good.  This increases the applicability and
> >> relevance of a summer project to a wider audience.
> >>
> >>
> >> On Thu, Mar 20, 2014 at 11:25 AM, Ondřej Čertík <[email protected]>
> >> wrote:
> >>>
> >>> On Thu, Mar 20, 2014 at 12:17 PM, Ondřej Čertík <[email protected]>
> >>> wrote:
> >>> > Hi Peter,
> >>> >
> >>> > I read through your ideas. First of all, I started SymPy as a
> >>> > theoretical physics student myself,
> >>> > and I wanted to automate the General Relativity as well as high
> energy
> >>> > QFT calculations. I am still
> >>> > very interested in that, but there are a lot of tough problems and
> >>> > parts that need to be in place.
> >>> >
> >>> > You need to be able to do integrals, handle potentially large
> >>> > formulas, tensor manipulation and simplification
> >>> > (e.g. gamma matrices), and so on. It's not easy at all, but we've
> done
> >>> > a long progress since the time I started
> >>> > SymPy in 2007 or so. Most of these things are in place, in some form.
> >>> > In order to efficiently handle very large
> >>> > expressions, I started developing CSymPy about half a year ago
> >>> > (https://github.com/certik/csympy), this
> >>> > will come very handy as well for these applications.
> >>> >
> >>> > The best way to get some ideas of what can be done is to look into
> >>> > existing packages, they are pretty much
> >>> > all in Mathematica. In fact, most theoretical physicist just use
> >>> > Mathematica. And let's be frank, it's currently the
> >>> > best if you just care about getting the results. There is also GiNaC
> >>> > (http://www.ginac.de/) that can be used for some of the
> >>> > high energy stuff, but CSymPy can now do pretty similar things,
> >>> > sometimes faster. So there is:
> >>> >
> >>> > http://www.feyncalc.org/
> >>> >
> >>> > there are all these various things people wrote for Mathematica:
> >>> >
> >>> > @article{huber2012crasydse,
> >>> >   title={CrasyDSE: A framework for solving Dyson--Schwinger
> equations},
> >>> >   author={Huber, Markus Q and Mitter, Mario},
> >>> >   journal={Computer Physics Communications},
> >>> >   volume={183},
> >>> >   number={11},
> >>> >   pages={2441--2457},
> >>> >   year={2012},
> >>> >   publisher={Elsevier}
> >>> > }
> >>> >
> >>> > @article{huber2012algorithmic,
> >>> >   title={Algorithmic derivation of functional renormalization group
> >>> > equations and Dyson--Schwinger equations},
> >>> >   author={Huber, Markus Q and Braun, Jens},
> >>> >   journal={Computer Physics Communications},
> >>> >   volume={183},
> >>> >   number={6},
> >>> >   pages={1290--1320},
> >>> >   year={2012},
> >>> >   publisher={Elsevier}
> >>> > }
> >>> >
> >>> > But the advantage of SymPy is that the whole stack is opensource, and
> >>> > SymPy is just a library, so it better integrates
> >>> > with things like IPython Notebook and you can create the whole
> >>> > application in it. For example, the physics.quantum
> >>> > module has some good stuff, that plays together much better than
> >>> > packages in Mathematica. Another great application is PyDy.
> >>> >
> >>> > So it would be really nice to have the project that you describe. You
> >>> > should have a look at work done by Francesco Bonazzi
> >>> > regarding the gamma matrices:
> >>> >
> >>> > https://github.com/Upabjojr
> >>> > https://github.com/sympy/sympy/pull/2601
> >>> >
> >>> > He has lots of PRs, closed and open. It's nontrivial. And those are
> >>> > just the gamma matrices. I think Francesco's goal
> >>> > could be summarized by your proposal, and he's done many months worth
> >>> > of work on it already. So the scope is just huge.
> >>> > So there is plenty of things that could be done for the summer.
> >>> >
> >>> > One of the things is for example just the Feynman diagrams generator
> >>> > for various Lagrangians. I am sure there must be some
> >>> > packages that do that, but it'd be nice to integrate this with SymPy
> >>> > and create nice IPython Notebooks that generate all the correct
> >>> > diagrams, for example from Peskin & Schroeder. This will be good for
> >>>
> >>> I.e. this would involve some classes for representation of Feynman
> >>> diagrams,
> >>> that would also know how to nicely visualize themselves in the IPython
> >>> Notebook,
> >>> and then code that generates them for various interactions.
> >>> And so on.
> >>>
> >>> For other ideas, I have some derivations of various things here:
> >>>
> >>> http://theoretical-physics.net/dev/src/quantum/qft.html#standard-model
> >>>
> >>> that could be automated. For example one can reformulate the problem
> >>> using
> >>> Green's functions and so on.
> >>>
> >>> Ondrej
> >>>
> >>> > pedagogical reasons, as well as computations. In general,
> >>> > good applications in my opinion are providing automatic symbolic
> >>> > solutions to various exercises from books.
> >>> >
> >>> > Another thing is of course Regularization and Renormalization.
> >>> >
> >>> > I would suggest you to figure out something, that can be finished
> >>> > during a summer and that would provide something useful,
> >>> > on it's own. So that you can create nice examples out of it. Then you
> >>> > can continue working on some other things after the summer.
> >>> >
> >>> > Ondrej
> >>>
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