On Wednesday, January 25, 2012, Nils Bruin <nbr...@sfu.ca> wrote: > On Jan 25, 9:22 am, Volker Braun <vbraun.n...@gmail.com> wrote: >> On Wednesday, January 25, 2012 8:58:15 AM UTC-8, Nils Bruin wrote: >> >> > sage: bool(37 +i < 37 -i) >> > False >> >> False meaning that Sage cannot affirm that it is true; IMHO the correct >> answer. >> >> > sage: bool(37 +i > 37 -i) >> > True >> >> BUG > Having "<" return always false would actually be worse in practice. > Then "sort" would not throw an error, but return unstable and > implementation-dependent results. > > sorting a list L of complex numbers without relying on "__cmp__" being > defined for complex numbers can by done via something along the lines > of > > sorted(L,key=list) > > or > > sorted(L,key=lambda a: (a.real(),a.imag())) > > The problem gets worse if you have to devise a "key" function on a > more heterogeneous collection of objects, though. If someone would > come up with a reasonable candidate, we could call it "total_ordering" > or something like that and then people would be able to invoke > > sorted(L,key=total_ordering) > > if they need to sort things without having to rely on arbitrary > orderings invading into notation that suggests more algebraic meaning > than is meant.
+1. That's an explicit redescription of exactly what I mentioned above... > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org > -- William Stein Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
