Hi Jamie, On Fri, Oct 31, 2014 at 10:53 AM, Jamie Titus <[email protected]> wrote: > Hello all, > > I was wondering if anybody knew what the status of the Tensor module is - > i.e., is work being done on it, what is the known functionality, and what is > the intended functionality. For the past week I have been attempting to use > Sympy for basic General Relativity (homework problems really), and it has > not gone well. My naive review of the documentation suggests that I should > be able to use Einstein Notation, since I am completely unfamiliar with > Penrose's abstract index notation (and it doesn't seem to be as useful > computationally, frankly, though the wikipedia article on it is very short). > However, I keep encountering errors when I try to do basic operations such > as add or multiply tensors, and I am never quite sure if they are bugs or > features. A minimal example is that when you attempt to symmetrize a tensor > you just get back double the tensor components, i.e., given a TensorHead A, > and indices i0, i1, A(i0, i1) + A(i1, i0) should be manifestly symmetric, > but it just results in 2*A(i0, i1). If necessary I can provide minimal > working examples in code. I wasn't sure if this is the right place for that.
Thanks for your feedback, yes, this is the right place to ask. Would you mind sending few snippets that you found confusing? > > If there is somebody who is acting as a contact for the Tensor module, I'd > very much like to know whether I'm encountering bugs or 'features.' If the > former, I'm willing to try to submit patches to fix some of the problems > that keep cropping up, or at least document them. I honestly found the > Tensor module very confusing from the standpoint of somebody who is > interested in solving simple GR problems, so I'd like to try to understand > the rationale behind it and make things clearer for other users. GR was one of the main applications that I wanted to use SymPy for when I started it. However, it was a lot of work to get the basic functionality working, so I never got to actually write the tensor module. Some people who worked on the tensor module are: Francesco Bonazzi Björn Dahlgren Mario Pernici ... Essentially if you go into the file and do "git blame", it tells you who wrote it. I would be very much interested in fixing it, so that it is easy to use for users. If you could send us all the things that surprised you, that would be a start. Then we can figure out how to best fix that. Many thanks, 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/CADDwiVBpe3j7eu8yJ%3DrPQHMEiu_GTGQ4SaEzQ-oY2Lg2wvsMXw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
