On Fri, Mar 20, 2009 at 6:58 AM, [email protected] <[email protected]> wrote: > Thanks for the suggestion. I have now looked at the relativity.py > file and believe it to be a reasonable start. Once I understand more > I will make some related changes and let you know what I get. Another
Excelllent. Btw, the way it is currently done is very inneficient --- for example for the Riemann tensor I am calculating all the coefficients of the Christoffel symbols over and over again. This should be cached. > related area is general relativistic fluid dynamics for which sympy > hopefully can be useful in generating eigenvectors and eigenvalues of > the Jacobian matrix of the conservative variables with respect to the > primitive variables. Also, using sympy to compute the residual of the > equations when studying the accuracy of computations based on > Einstein's equations (Numerical Relativity) could be useful. These > kinds of computations are currently done using Mma. These are just a > few things which it would be nice to demonstrate can be handled by > sympy. That is very cool. How are you solving the Einstein's equations? Spectral elements? Or finite differences? Or some other method? Is there an application for finite elements? If so, then the whole group that I am at could be interested in that, feel free to browse what we do here: http://hpfem.org/ http://hpfem.math.unr.edu/ > On a related topic, what do you think is the problem with tensor.py? > I can see a need for the approach which seems to be contained therein, > namely evaluation of expressions involving products of various tensors > of various ranks in things like: > > T^{abcd}_{ef} * Z_{ad} * W_{b} * Q_{bc} where a,b,c, and d run over > {0,1,2,3}. > > Such expressions are used in Numerical Relativity codes and are quite > unwieldy to generate by hand. Having sympy do this would be cool and > maybe even useful. I started to write code for this in this issue: http://code.google.com/p/sympy/issues/detail?id=16 as you can see, it is a very old issue. :) So it just needs to be finished. I am very interested in sympy being useful for your research and maybe you'll find other ways that we can collaborate on this, see above. Ondrej --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sympy?hl=en -~----------~----~----~----~------~----~------~--~---
