On Tue, Feb 3, 2015 at 1:52 PM, Francesco Bonazzi <franz.bona...@gmail.com> wrote:
> > On Tuesday, February 3, 2015 at 8:18:58 PM UTC+1, Aaron Meurer wrote: > >> Do physics applications actually use summation notation with noninteger >> limits? If so, what convention do they use? >> > > Summing over the states of fermions. But that's a convention. > > >> @asmeurer. I only know they are used in summing the "half-integer" spins. >> But i have no idea regarding the rules used. >> > > Spins are usually half-integers in spacetime, but I know of some special > cases, like propagation on waves on 2D surfaces, where one may build a > theory with any rational spin quasi-particles, or something like that. > > Sometimes people with a background in mathematics get really scared when > they see how mathematics is used in physics. The funniest I can think of is > that multiple summations and integrals are often silently assumed to > commute, even if they sum over to infinity. > But do they actually use summation convention, as if i=0.5..2.5 meant i = 0.5, 1.5, 2.5? I guess you make a good point, in that I wouldn't completely trust it even if they did, because I doubt physicists would have thought through all the mathematical implications of choosing that convention, which is something that we do need to care about. Aaron Meurer > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > Visit this group at http://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/be18856c-e61c-4711-a5a4-b52194b306e6%40googlegroups.com > <https://groups.google.com/d/msgid/sympy/be18856c-e61c-4711-a5a4-b52194b306e6%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6KAvvRQBu_PSYY-C_aJTQOKmJdMDyNumpTkF22N3jU7eQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
