Le vendredi 18 mars 2011 à 16:29 +0530, Hector a écrit :
> Yes, exactly. > It seems more consistent that way. Has this issue already been > discussed? If not, do we need to report this? > Since I am looking forward to apply for GSoC, and would love to work > with SymPy, this would be good start for me. > > If core developers/contributors agree, I would like to work on this > regardless GSoC. Because with thing implemented, we can never go for > limit of multi-variable functions. I thought about this before, but I didn't reach the point where I could suggest a design. I think there needs to be an object describing the "destination" of a limit (i.e. "0", "0+", "0-", "+oo", ...), so the syntax for limit would be limit(f(x), x, <something that means "0+">) instead of limit(f(x), x, 0, dir="+"). These destination objects would also be used by series() and the like and would be passed around in the internal code. The proper mathematical notion corresponding to this is a filter[*]. It applies also in the multivariate case and allows to describe limits when |(x,y)| -> 0, or when (x,y) -> (0,0) along a particular ray or some more complicated curve, etc. [*]: See http://fr.wikipedia.org/wiki/Filtre_%28math%C3%A9matiques%29 (in French) - I couldn't find a good description in English. The en.Wikipedia article in particular is so full of category-theoretic abstract nonsense as to be useless. -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
