I think you guys are perhaps talking past each other. To Ondrej, "series" means "series approximation", whereas to "Sartaj" it menas "formal power series". Both are mathematically related, but from a CAS point of view they are quite different.
Formal power series is something that would be nice for SymPy to have, but my understanding is that the summation algorithms will need to improve a lot for you to be able to compute anything nontrivial (like Cauchy products). Aaron Meurer On Mon, Mar 23, 2015 at 7:12 PM, Ondřej Čertík <[email protected]> wrote: > On Mon, Mar 23, 2015 at 1:41 AM, Sartaj Singh <[email protected]> wrote: >> It looks like ring_series, works only for finite cases, can it be extended >> for infinite case? SeriesData will just zip two sequences together. It is >> more general as variables can even be of the form sin(n*x), and not only x. >> In the main FormalPowerSeries class, I plan to provide an infinite >> representation of series. > > I think the ring series can only be used for n terms, i.e. if you have > some expression, like sin(x)*cos(x), then you first expand sin(x) and > cos(x) into n-terms, and then you multiply them out, and cut the > result appropriately (at n-terms in this case). > > But you can use any "n". How do you store infinite number of terms in > your approach? > >> Ring_series is undoubtedly fast, so it is a plus to use it in my >> implementation. I have glanced over the code of ring_series, and it may be >> modeled into the structure I propose, i.e based on sequences. The algorithms >> in ring_series can be used for manipulating truncated form of the series. >> >> In summary, I think SeriesData should be left as a higher abstraction, and >> operations for truncated series can be added in SeriesX or in >> FormalPowerSeries. Let me know what you think. > > That would work. > > 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/CADDwiVBTqTBBFCUUu_pgXNyvAibPU2ObX3_JMVQac8YAk1MtiQ%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/CAKgW%3D6KOztzRP3KKfy%3D5Bz3Ar7UQG4mCF5OmTLX%2BipPPJ7CByA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
