@Matthew, in general I would agree, but the algorithms for translating "Lagrangian -> Feynman rules" or "Feynman rules + initial and final state -> differential cross section" are already both 1) non trivial and 2) domain specific. Abstracting this away might not be worth it as it is not really used anywhere else.
(but where it is used, it is used a lot. There is an entire standard around it (UFO model files and Les Houches dump files as described in the FeynRules and MadGraph projects)) Exception: It might be useful in calculating correlations of some multivariate functions through series expansions. That might we worth investigating somewhat more. On 20 March 2014 14:34, Matthew Rocklin <[email protected]> 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 >> >> -- >> 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/CADDwiVCdh9JHMZ%3DQeUMK1-xrcXhjOY4JraWcs5OmnrzsJnZRZg%40mail.gmail.com. >> For more options, visit https://groups.google.com/d/optout. > > > -- > 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/CAJ8oX-EyLMkyEpgbqdbEvx5X6Y4ar96W0r6EzfELmZF18J_7UA%40mail.gmail.com. > > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sympy" group. 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