Thank you all for the speedy turnaround on this! In particular: Vincent and Dima: Thank you for the informative 'code archaeology' and helpful pointers Dave: Thank you for filing (and fixing!) #31645 <https://trac.sagemath.org/ticket/31645>
Best, Thomas On Sun, Apr 11, 2021 at 12:53 AM [email protected] < [email protected]> wrote: > Thanks for reporting the bug. It is now trac ticket #31645 > <https://trac.sagemath.org/ticket/31645>, and I expect to upload a fix > soon. > > On Friday, April 9, 2021 at 9:29:26 AM UTC-6 [email protected] wrote: > >> On Fri, Apr 9, 2021 at 4:09 PM Vincent Delecroix >> <[email protected]> wrote: >> > >> > Thanks for the bug report. >> > >> > If you know how to proceed, please open a ticket and post the url here. >> > >> > - series goes through the ginac library (which is full of bugs and we >> > are trying to get rid off it) >> >> more precisely, it's our fork of ginac, pynac, that is buggy, and it >> has diverged from ginac quite a bit, >> so it's unfair to blame ginac, the original upstream; >> unfortunately the people who used to develop pynac have more or less >> left the project. >> >> >> >> > - taylor goes through maxima which is much more reliable >> > >> > The sympy library offers a nice alternative for symbolic computations. >> > >> > Best >> > Vincent >> > >> > Le 09/04/2021 à 16:01, TBK a écrit : >> > > To Whom it May Concern: >> > > >> > > Per the "Reporting Bugs" procedure >> > > <https://doc.sagemath.org/html/en/developer/trac.html#reporting-bugs>, >> I am >> > > emailing sage-devel@ with a suspected bug. I am happy to open a TRAC >> > > ticket, if appropriate. >> > > >> > > I'm getting some seemingly incorrect series expansions. In >> particular, >> > > adding a constant is sometimes introducing an $x^{-1}$ term instead >> of an >> > > $x^0$ term. I have included below a fairly minimal repro. Sage >> correctly >> > > expands `(1-sqrt(1-x))/x`. However, sage insists that adding `123` >> > > introduces a `123*x^-1` term. Using `taylor()`, I get the expected >> > > expansion in both cases. >> > > >> > > This seems obviously incorrect, but I am new to sage so apologize if >> this >> > > is just pilot error. I looked for existing threads on power series >> bugs. >> > > The closest I found was this message >> > > <https://groups.google.com/g/sage-devel/c/_rB24fZSHKs/m/XneaemQ4AgAJ> >> asserting >> > > that the combinatorial species code has long been riddled with bugs. >> If >> > > this is a bug, is taylor() believed to be less bug-riddled? >> > > >> > > >> > > *Repro:* >> > > {{{ >> > > sage: ((1-sqrt(1-x))/x + 0).series(x,3) >> > > >> > > 1/2 + 1/8*x + 1/16*x^2 + Order(x^3) # correct >> > > sage: ((1-sqrt(1-x))/x + 123).series(x,3) >> > > >> > > 123*x^(-1) + 1/2 + 1/8*x + 1/16*x^2 + Order(x^3) # ??? >> > > # taylor() correctly expands both >> > > sage: taylor((1-sqrt(1-x))/x + 0,x,0,2) >> > > >> > > 1/16*x^2 + 1/8*x + 1/2 >> > > sage: taylor((1-sqrt(1-x))/x + 123,x,0,2) >> > > >> > > 1/16*x^2 + 1/8*x + 247/2 >> > > }}} >> > > >> > > *Version:* >> > > │ SageMath version 9.2, Release Date: 2020-10-24 │ >> > > │ Using Python 3.8.5. Type "help()" for help. │ >> > > *OS*: macOS Catalina (10.15.7) (64-bit x86) >> > > >> > > Best, >> > > Thomas >> > > >> > > >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups "sage-devel" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an email to [email protected]. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/sage-devel/710d3756-f93a-731e-b945-a23b48fe9fe8%40gmail.com. >> >> > -- > You received this message because you are subscribed to a topic in the > Google Groups "sage-devel" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sage-devel/av4L3qQZl0o/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sage-devel/31abf163-7770-4d24-bd17-a95fcb7486d8n%40googlegroups.com > <https://groups.google.com/d/msgid/sage-devel/31abf163-7770-4d24-bd17-a95fcb7486d8n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/CACM7bJWKoGNkZm40FOnx9LdxgW2OUoeFyoo2pKE1DSZ51V%3DcMg%40mail.gmail.com.
