Here's another curious test: If I run this in Sage:
(x^2+2*x+1)/(x+1) then the output is itself. If I run: (x+1)^2/(x+1) then the output is x+1. The interesting thing is that feeding either of the above to the solve command results in the "solution" x==-1. So merely "running" does not always do the same simplifying that the solve command does. On Tuesday, March 21, 2017 at 1:52:42 PM UTC-10, William Stein wrote: > > On Tue, Mar 21, 2017 at 4:42 PM, Aaron Tresham <[email protected] > <javascript:>> wrote: > > OK, so Sage is doing this before calling Maxima. > > Yes. More precisely, probably http://www.ginac.de/ > > > > > It's probably more important that Sage simplify in general, so I will > just > > have to watch out for this (and warn my students). > > > > Thank you, > > Aaron > > > > On Tuesday, March 21, 2017 at 1:29:25 PM UTC-10, William Stein wrote: > >> > >> > >> On Tue, Mar 21, 2017 at 4:28 PM Aaron Tresham <[email protected]> > wrote: > >>> > >>> If I run x^2/x in SMC, the output is x. > >> > >> > >> That is what is really going on here. Maxima isn't relevant at all. By > the > >> time maxima sees your input, x^2/x has already beeb simplified to c. > >> > >> > >> > >>> > >>> That is fine in some contexts (although the user should mentally add > "x > >>> not equal to 0"). > >>> > >>> I'm dealing with rational functions with holes, and Sage is > eliminating > >>> the hole. Of course, it would be very nice if my students would notice > the > >>> hole themselves. > >>> > >>> Aaron > >>> > >>> > >>> On Tuesday, March 21, 2017 at 12:52:07 PM UTC-10, William Stein wrote: > >>>> > >>>> What happens if you just type x^2/x ? > >>>> > >>>> On Tue, Mar 21, 2017 at 3:35 PM Aaron Tresham <[email protected]> > wrote: > >>>>> > >>>>> Does anyone know if there is a similar group to discuss issues with > >>>>> Maxima? (I think that's where my problem lies). > >>>>> > >>>>> When I do something like: > >>>>> > >>>>> solve(x^2/x==0,x) > >>>>> > >>>>> I expect no solutions, but Sage gives me one solution, x==0. I'm > >>>>> assuming Sage uses Maxima here, and Maxima simplifies the fraction > before > >>>>> solving (and fails to check afterwards). I can catch things like > this > >>>>> myself, but I'm not sure my students would notice (especially if a > hole is > >>>>> hidden inside a complicated rational function). > >>>>> > >>>>> Thanks, > >>>>> Aaron > >>>>> > >>>>> -- > >>>>> You received this message because you are subscribed to the Google > >>>>> Groups "sage-cloud" 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-cloud/57f370bf-76ba-4bf5-8a20-8e1c0ba1201e%40googlegroups.com. > > > >>>>> For more options, visit https://groups.google.com/d/optout. > >>>> > >>>> -- > >>>> > >>>> Best Regards, > >>>> William Stein > >>>> > >>>> CEO, SageMath, Inc. > >>> > >>> -- > >>> You received this message because you are subscribed to the Google > Groups > >>> "sage-cloud" 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-cloud/948c7fc8-9ea2-4e3c-aa54-aecfafaf7b35%40googlegroups.com. > > > >>> For more options, visit https://groups.google.com/d/optout. > >> > >> -- > >> > >> Best Regards, > >> William Stein > >> > >> CEO, SageMath, Inc. > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "sage-cloud" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to [email protected] <javascript:>. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/sage-cloud/3ce2881f-e90c-45a0-9843-fab47dfde0bf%40googlegroups.com. > > > > > > For more options, visit https://groups.google.com/d/optout. > > > > -- > > Best Regards, > William Stein > > CEO, SageMath, Inc. > -- You received this message because you are subscribed to the Google Groups "sage-cloud" 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-cloud/513be4f6-8a80-42cb-8df2-260f1d4c44cc%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
