I am not sure of IndexSet usage but the reason I thought of it was that whenever we need to represent arbitrary set we have a notion of indexing so that is why I thought of having IndexSet. https://math.stackexchange.com/questions/485244/indexed-families-and-arbitrary-sets-notation http://www.math.umaine.edu/~farlow/sec22.pdf
> And you still haven't answered where infinite unions are needed for solveset. I thought of using BigUnion where there is a union of more than one imagesets, (like in case of trigonometric equations) >>> solveset(sin(x), x, S.Reals) Union(ImageSet(Lambda(_n, 2*_n*pi), S.Integers), ImageSet(Lambda(_n, 2*_n*pi + pi), S.Integers)) # (sin(2*x) + sin(4*x) + sin(6*x)) will have lots of union of imagesets BigUnion could give `ImageSet(Lambda(_n, _n*pi), S.Integers)`, (although _union of imageset is under development, BigUnion can act as helper) I guess this is an idea that is in an initial stage (and that is why I can't imagine it in larger scale), and if you suggest that it won't be feasible I would rather remove it from the proposal. Thanks Yathartha On Friday, March 23, 2018 at 11:56:03 AM UTC+5:30, Aaron Meurer wrote: > > I'm not seeing an instance where IndexSet is useful. For finite > collections of sets, it is redundant, as Union and Intersection can > already take a finite number of arguments. For infinite collections, > whatever symbol you index over would already exist in the collection > itself (for instance, n in Interval(2*n, 2*n + 1)) > > And you still haven't answered where infinite unions are needed for > solveset. > > Aaron Meurer > > On Fri, Mar 23, 2018 at 12:14 AM, Yathartha Joshi <yatha...@gmail.com > <javascript:>> wrote: > > What I understood about BigUnion and BigIntersection from here. BigUnion > for > > set of finitesets will work similar to union but for set of imagesets > > (infinite sets) we will be returning a unified solution. > > > > say for eg: [2*n , 2*n - 1 for n in Integers] passing it to Bigunion > will > > yield something like [n for n in Integers] and BigIntersection would > yield > > EmptySet. > > > > See https://github.com/sympy/sympy/issues/9815#issuecomment-373978030 > > > > In solveset when union of imagesets are returned we can apply big union > to > > get the unified result (probably could help the _union of imagesets once > its > > implemented). > > > > IndexSet will be implemented to get access to set of sets through > indexing, > > a number of sets will be passed as parameters and an instance of > IndexSet > > will be returned with indices mapped to each of the sets in the sets. > This > > way we can get access to a set of sets. > > > >>>> X = IndexSet(FiniteSet(1, 2, ,3), FiniteSet(4, 5)); X > >>>> X[0] > > FiniteSet(1, 2 ,3) > >>>>X[1] > > FiniteSet(4, 5) > > > > > > On Friday, March 23, 2018 at 5:44:13 AM UTC+5:30, Aaron Meurer wrote: > >> > >> Regarding BigUnion, what is the point of having it and IndexSet that > >> can only represent a finite number of sets? Union can already do this > >> without the indirection. I'm also unclear where this will be needed > >> for solveset. > >> > >> Aaron Meurer > >> > >> On Thu, Mar 22, 2018 at 4:38 PM, Yathartha Joshi <yatha...@gmail.com> > >> wrote: > >> > Sorry I just gave the access to amit kumar, I have changed it, please > >> > have a > >> > look. > >> > > >> > Thanks! > >> > > >> > > >> > On Friday, March 23, 2018 at 1:54:31 AM UTC+5:30, Aaron Meurer wrote: > >> >> > >> >> When I click on that link it says I don't have access. > >> >> > >> >> I recommend starting your proposal on > >> >> https://summerofcode.withgoogle.com and linking the draft proposal > >> >> there. That will make it easier to find in the future. > >> >> > >> >> Aaron Meurer > >> >> > >> >> On Thu, Mar 22, 2018 at 4:01 PM, Yathartha Joshi <yatha...@gmail.com> > > >> >> wrote: > >> >> > I have created a proposal here. It would be great if you could > review > >> >> > it > >> >> > and > >> >> > suggest any changes. > >> >> > > >> >> > Thanks in advance. > >> >> > Yathartha > >> >> > > >> >> > On Thursday, March 22, 2018 at 11:08:27 PM UTC+5:30, Yathartha > Joshi > >> >> > wrote: > >> >> >> > >> >> >> > >> >> >> On Thursday, March 22, 2018 at 2:26:18 PM UTC+5:30, Amit Kumar > >> >> >> wrote: > >> >> >>> > >> >> >>> Hey Yathartha, > >> >> >>> > >> >> >>> That sounds good. > >> >> >>> > >> >> >>> Cheers! > >> >> >>> Amit > >> >> >> > >> >> >> > >> >> >> Okay! Thanks. > >> >> >> > >> >> >> Also, I was thinking was making absolute value expressions to > work > >> >> >> in > >> >> >> complex domain. I found a few equations that have complex > solutions: > >> >> >> > >> >> >> > >> >> >> > http://www.wolframalpha.com/input/?i=solve(abs(x-2)+%2Babs(x)+-+7,+x) > >> >> >> http://www.wolframalpha.com/input/?i=solve(abs(x-2)+-2+,+x) > >> >> >> > >> >> >> > >> >> >> > >> >> >> > http://www.wolframalpha.com/input/?i=solve(abs(x-2)+%2Babs(x+%2B4)+-+16,+x) > >> >> >> > >> >> >> I was trying to figure out a possible way to solve this, but I am > >> >> >> facing > >> >> >> difficulty in getting to the solution. I tried asking the > question > >> >> >> here, and > >> >> >> got the only possible way. Can you provide me with some > suggestions > >> >> >> regarding this? Is there a specific reason as to why solveset > (and > >> >> >> even > >> >> >> solve) is not made to solve in complex domain. > >> >> >> > >> >> > -- > >> >> > 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 sympy+un...@googlegroups.com. > >> >> > To post to this group, send email to sy...@googlegroups.com. > >> >> > Visit this group at https://groups.google.com/group/sympy. > >> >> > To view this discussion on the web visit > >> >> > > >> >> > > >> >> > > https://groups.google.com/d/msgid/sympy/aecef52c-4e2e-40b0-9b1c-3cf7c022374c%40googlegroups.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 sympy+un...@googlegroups.com. > >> > To post to this group, send email to sy...@googlegroups.com. > >> > Visit this group at https://groups.google.com/group/sympy. > >> > To view this discussion on the web visit > >> > > >> > > https://groups.google.com/d/msgid/sympy/862ac528-e77b-46e6-b751-e5ef532a2e46%40googlegroups.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 sympy+un...@googlegroups.com <javascript:>. > > To post to this group, send email to sy...@googlegroups.com > <javascript:>. > > Visit this group at https://groups.google.com/group/sympy. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/sympy/34765644-ae2a-4332-9a17-52e54c056f9c%40googlegroups.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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