On Sun, Jan 19, 2014 at 12:48 AM, Matthew Rocklin <[email protected]> wrote: > FYI we renamed TransformationSet to ImageSet
Oh, I was going to say ImageSet but that didn't sound right. > > The boolean predicate bit can be expressed as an intersection with the > indicator set of the predicate. Is this something that is already implemented? I also don't see how you would do this. Are you saying that we should have https://en.wikipedia.org/wiki/Indicator_function, and then represent the set as the inverse image of 1? That may be circular, and it's somewhat convoluted. And I don't think we have an inverse image set yet. > > It sounds like maybe solve should return a Set. Yes, or some kind of SolveSet object that wraps one (I don't remember but there may be some need for extra methods that don't make sense on general sets). > > > On Sat, Jan 18, 2014 at 10:39 PM, Aaron Meurer <[email protected]> wrote: >> >> > On Jan 19, 2014, at 12:25 AM, Harsh Gupta <[email protected]> >> > wrote: >> > >> > I'm working on imageset at https://github.com/sympy/sympy/pull/2723 >> > and as you said it needs solve to give all the solutions. But I didn't >> > know that solve >> > may not give all the solutions even if there are only a finite number of >> > them. >> > Documentation doesn't state that, I'll try to add that asap. >> >> It's mentioned in the tutorial. The issue is twofold. One is that >> solve is mostly heuristics, so it may miss things, and the other is >> that some expressions have solutions that aren't closed-form >> expressible, like cos(x) = x. >> >> > >> > I saw this also on the GSOC ideas page and I would like to work on it. >> >> Yes, I just added this today, because this issue reminded me of it. As >> is noted on the page, for this project it would really be best to >> flesh out the details in the application (meaning we should start >> discussing them now). >> >> > >> > I think we should implement a good way to represent and handle, infinite >> > sets. >> > Maybe something extending the current Naturals and Integers sets. >> > Matthew can >> > you point me some resources that deals with handling infinite sets. >> >> I think with TransformationSet we can do quite a bit. That handles >> sets like {f(x) | x in A}. I think what is missing is the basic set >> builder {x | P(x)}, where P(x) is a boolean predicate. >> >> Aaron Meurer >> >> > >> > -- >> > 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. >> > For more options, visit https://groups.google.com/groups/opt_out. >> >> -- >> 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. >> For more options, visit https://groups.google.com/groups/opt_out. > > > -- > 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. > For more options, visit https://groups.google.com/groups/opt_out. -- 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. For more options, visit https://groups.google.com/groups/opt_out.
