Just FYI this has been fixed upstream: https://sourceforge.net/p/maxima/bugs/4634/ so hopefully in a future version of Maxima soon.
Question to Nils or others: In the past we used to also open a ticket for Sage to make our own doctest - is that still the practice? I'm just making a note at #40679 for now. On Tuesday, November 18, 2025 at 12:55:27 PM UTC-5 [email protected] wrote: > Thank you all for looking into this. I'm happy to hear that the bug has > been fixed in Maxima. I'm sure the fix will work it's way into Sage soon > enough. > > By the way, this sum did return "und" a few years ago, and later the > answer changed to "ind" (before changing to -1/4). I agree that und is > better than ind (as far as I understand the difference between these). > > Aaron > > On Tuesday, November 18, 2025 at 4:42:01 AM UTC-10 kcrisman wrote: > >> Thanks for pointing that one out, that's great. >> >> (Though note that apparently the "correct" answer is "und" not "ind", >> according to the latest comment on the Sourceforge ticket!) >> >> On Tuesday, November 18, 2025 at 8:14:01 AM UTC-5 Antonio Rojas wrote: >> >>> This is fixed in maxima 5.48. The upgrade ticket is >>> https://github.com/sagemath/sage/pull/40679 >>> >>> El martes, 18 de noviembre de 2025 a las 13:59:27 UTC+1, kcrisman >>> escribió: >>> >>>> I've opened https://sourceforge.net/p/maxima/bugs/4634/ for this, and >>>> hopefully we'll hear back. Can someone open a corresponding Sage ticket >>>> which will eventually get a doctest for the same? Thanks! >>>> >>>> On Monday, November 17, 2025 at 10:38:54 PM UTC-5 Nils Bruin wrote: >>>> >>>>> I can confirm the behaviour you're observing ... It's really >>>>> unfortunate!. This would be a result produced by maxima, so most likely >>>>> it's a change due to a change in maxima version. I would call it a bug. >>>>> One >>>>> should probably try to reproduce it in maxima proper and then report it >>>>> to >>>>> maxima. Hopefully they can fix it. >>>>> >>>>> In maxima 5.47.0 I get: >>>>> >>>>> (%i1) load(simplify_sum)$ >>>>> (%i2) simplify_sum( sum(n*(-1)^n,n,1,inf)); >>>>> -1/4 >>>>> >>>>> This happens both on sage's ECL based one and on the system maxima >>>>> (running on SBCL). So I think this behaviour tracks decisively to maxima. >>>>> >>>>> On Monday, 17 November 2025 at 19:23:53 UTC-8 [email protected] wrote: >>>>> >>>>>> I have used SageMath within CoCalc for teaching Calculus 2 for >>>>>> several years. >>>>>> >>>>>> In past semesters, the following code produced the output "ind": >>>>>> >>>>>> var('n') >>>>>> sum(n*(-1)^n,n,1,oo) >>>>>> >>>>>> This is expected, since the series diverges. >>>>>> >>>>>> However, this semester I changed the kernel from SageMath 10.4 to the >>>>>> current SageMath 10.7. Now this same code produces the output "-1/4" [I >>>>>> believe 10.5 and 10.6 behave the same way as 10.7.] >>>>>> >>>>>> I have my students compute the value of several similar series >>>>>> (replacing the -1 in the code above with -2, -1/2, 1/2, 1, and 2), and >>>>>> all >>>>>> the others are behaving the same way they always have. It is only this >>>>>> series which is giving me an unexpected output. >>>>>> >>>>>> Has anyone else encountered this issue? >>>>>> >>>>>> Thanks, >>>>>> Aaron >>>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/sage-support/0beb1c12-5d31-4dd4-a9ac-b92b56b09a65n%40googlegroups.com.
