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/6291b999-e33c-4b12-a5a3-af43d2db521an%40googlegroups.com.
