I confirm the issue with the Taylor series with Sage 9.1. Fortunately, the bug seems to have been fixed for Sage 9.2. As Emmanuel, I get the correct Taylor series with Sage 9.2.beta13.
Le mardi 29 septembre 2020 à 09:36:09 UTC+2, Emmanuel Charpentier a écrit : > I can’t reproduce your problem : > > sage: sage.version.version > '9.2.beta13' > sage: var('t') > t > sage: assume(x>0) > sage: f(x)=integrate(sin(t)/t,t,0,x) > sage: f > x |--> sin_integral(x) > sage: taylor(f(x),x,0,10) > 1/3265920*x^9 - 1/35280*x^7 + 1/600*x^5 - 1/18*x^3 + x > > My platform is Debian testing running on core i7 + 16 GB RAM ; sage is > built to use as much system packages as possible. hat are your platforms ? > > HTH, > Le lundi 28 septembre 2020 à 22:03:56 UTC+2, fqgo...@colby.edu a écrit : > >> I am trying to see how to do a standard calculus exercise in Sage. I want >> a power series for the integral of sin(x)/x. I tried: >> >> sage: var('t') >> t >> sage: assume(x>0) >> sage: f(x)=integrate(sin(t)/t,t,0,x) >> sage: f >> x |--> sin_integral(x) >> sage: taylor(f(x),x,0,10) >> 73/466560*x^9 - 127/35280*x^7 + 31/600*x^5 - 7/18*x^3 + x >> >> The first weirdness is that Sage can't compute the integral unless I add >> the "assume(x>0)"; I'm not sure why. >> >> The second weirdness is that the Taylor series is wrong! >> Taylor(Si(x),x,0,10) gives the same answer. >> >> Fernando >> >> >> -- >> ================================================================== >> Fernando Q. Gouvea >> Carter Professor of Mathematics >> Colby College >> Mayflower Hill 5836 >> Waterville, ME 04901 fqgo...@colby.edu >> http://www.colby.edu/~fqgouvea >> >> The object of opening the mind, as of opening the mouth, is to shut it >> again on something solid. >> -- G. K. Chesterton, Autobiography. >> >> >> -- 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 sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/fa8ad53c-16e3-46ad-8d73-c2b7a28224acn%40googlegroups.com.