On Wed, Mar 20, 2019 at 1:37 PM Dima Pasechnik <dimp...@gmail.com> wrote: > > On Wed, Mar 20, 2019 at 1:27 PM mmarco <mma...@unizar.es> wrote: > > > > So the bug is really in the abs_integrate package for maxima? In that case: > > is it really worth it to import it by default? > > removing it makes 7 tests fail in src/sage/interfaces/maxima_lib.py > > perhaps it should be applied more intelligently, but this seems to > require parsing for abs() and sgn()...
I would not mind to see not loading abs_integrate by default, and modifications to examples and tests to explicitly load abs_integrate before running affected examples... > > > > > > > El miércoles, 20 de marzo de 2019, 13:58:46 (UTC+1), Dima Pasechnik > > escribió: > >> > >> On Wed, Mar 20, 2019 at 05:36:59AM -0700, mmarco wrote: > >> > I am trying to pinpoint the following bug: > >> > > >> > sage: integral(sqrt(1+cos(x)^2),x) > >> > -1/24*sin(3*x) + 1/8*sin(x) > >> > > >> > > >> > which is incorrect. One would think that maxima is returning a wrong > >> > answer, but if we ask directly to maxima, it leaves the integral as it > >> > is: > >> indeed, it is an elliptic integral, cannot be done in elementary > >> functions. > >> > >> The problem comes from src/sage/interfaces/maxima_lib.py > >> loading abs_integrate: > >> > >> sage --maxima > >> ;;; Loading #P"/mnt/opt/Sage/sage-dev/local/lib/ecl/sb-bsd-sockets.fas" > >> ;;; Loading #P"/mnt/opt/Sage/sage-dev/local/lib/ecl/sockets.fas" > >> ;;; Loading #P"/mnt/opt/Sage/sage-dev/local/lib/ecl/defsystem.fas" > >> ;;; Loading #P"/mnt/opt/Sage/sage-dev/local/lib/ecl/cmp.fas" > >> Maxima 5.41.0 http://maxima.sourceforge.net > >> using Lisp ECL 16.1.2 > >> Distributed under the GNU Public License. See the file COPYING. > >> Dedicated to the memory of William Schelter. > >> The function bug_report() provides bug reporting information. > >> (%i1) load(abs_integrate); > >> ARRSTORE: use_fast_arrays=false; allocate a new property hash table for > >> $INTABLE2 > >> (%o1) > >> /mnt/opt/Sage/sage-dev/local/share/maxima/5.41.0/share/contrib/integrati\ > >> on/abs_integrate.mac > >> (%i3) display2d : false; > >> (%o3) false > >> (%i4) integrate(sqrt(1+cos(x)^2),x); > >> > >> (%o4) ((2*sin(3*x)+6*sin(x))*false-sin(3*x)+3*sin(x))/24 > >> > >> Which does not make much sense, and apparently Sage gets the bit of it > >> after "false"... > >> > >> Dima > >> > > >> > sage: f = sqrt(1+cos(x)^2) > >> > sage: maxima.integrate(f._maxima_(),x) > >> > 'integrate(sqrt(cos(_SAGE_VAR_x)^2+1),_SAGE_VAR_x) > >> > > >> > which is the same result we get with sympy and fricas, and even by maxima > >> > itself: > >> > > >> > Maxima 5.41.0 http://maxima.sourceforge.net > >> > using Lisp ECL 16.1.2 > >> > Distributed under the GNU Public License. See the file COPYING. > >> > Dedicated to the memory of William Schelter. > >> > The function bug_report() provides bug reporting information. > >> > (%i1) integrate(sqrt(1+cos(x)^2),x); > >> > / > >> > [ 2 > >> > (%o1) I sqrt(cos (x) + 1) dx > >> > ] > >> > / > >> > > >> > So something strange is going on when we call maxima internally to > >> > compute > >> > that integral. I have tried to trace it, but I got lost in the > >> > intrincancies of the maxima interface. > >> > > >> > Does somebody know what exactly is causing this discrepancy? > >> > > >> > -- > >> > 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 sage-devel+...@googlegroups.com. > >> > To post to this group, send email to sage-...@googlegroups.com. > >> > Visit this group at https://groups.google.com/group/sage-devel. > >> > For more options, visit https://groups.google.com/d/optout. > >> > > -- > > 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 sage-devel+unsubscr...@googlegroups.com. > > To post to this group, send email to sage-devel@googlegroups.com. > > Visit this group at https://groups.google.com/group/sage-devel. > > For more options, visit https://groups.google.com/d/optout. -- 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 sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
