18.03.2011 13:59, Hector пишет:
On Fri, Mar 18, 2011 at 4:14 PM, Alexey U. Gudchenko<pr...@goodok.ru>wrote:
From your remarks I see that you want to define dir="unknown" or dir="both"
as default. And in this case of 'dir' limit should return "None" for
"abs(x)/x" (when result differ between dir="-" and dir="+"). Right?
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 don't know now the situation with organization of limit's branches
exactly (on some of them the job can be proceeding now).
Chris Smith or others can up to date about it.
And, as I understand, the algorithm of this behavior implementation
seems to be easy in real axes - it differ dir="+" and dir="-".
And, we must determine a little things, which variant is more convenient:
dir="unknown" | "both" | "any"
I tend to "unknown", "any" (keeping in mind multi variable case), though
one can imagine further the distinguish between "any" and "unknown":
>>> limit(abs(x)/x, x, 0, dir="+")
1
>>> limit(abs(x)/x, x, 0, dir="unknown")
None
>>> limit(abs(x)/x, x, 0, dir="any")
[{-1: dir="-"}, {1: dir="+"] # something like cases as Piecewise
(But towards to the future for multi variable cases, and *even for
complex variable* the algorithm it seems should be more intelligent)
That is all what I can write about this theme.
I think in a few hours, after others will add some remarks, issues will
be ready.
--
Alexey U.
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