On Thu, Jun 24, 2021 at 8:40 AM David Bailey wrote:
>
> On 23/06/2021 23:15, Oscar Benjamin wrote:
> > There are some useful things that you can do with zoo like:
> >
> > In [1]: 1/zoo
> > Out[1]: 0
> >
> I suppose I might question the word 'useful' in your example! I mean oo
> is clearly
On 23/06/2021 23:15, Oscar Benjamin wrote:
There are some useful things that you can do with zoo like:
In [1]: 1/zoo
Out[1]: 0
I suppose I might question the word 'useful' in your example! I mean oo
is clearly extremely useful for limits, integrals, etc, but zoo isn't,
because its phase is
There are some useful things that you can do with zoo like:
In [1]: 1/zoo
Out[1]: 0
If it weren't for things like this then I think exceptions would
always be better.
--
Oscar
On Wed, 23 Jun 2021 at 22:49, Aaron Meurer wrote:
>
> Complex infinity is a mathematically meaningful object, and
Complex infinity is a mathematically meaningful object, and SymPy
generally prefers to give mathematically meaningful results when it
can, even if they are unevaluated. You're right that if you get zoo
out of something it usually means you made a mistake somewhere, but it
is also possible to use
On 21/06/2021 23:13, Aaron Meurer wrote:
It's worth noting that if you used a Jupyter notebook with LaTeX
output, zoo prints in a nice way (\tilde{\infty}), that makes it
easier to tell what it is.
The problem with printing oo and zoo in longer form is that it makes
things more verbose,
It's worth noting that if you used a Jupyter notebook with LaTeX
output, zoo prints in a nice way (\tilde{\infty}), that makes it
easier to tell what it is.
The problem with printing oo and zoo in longer form is that it makes
things more verbose, especially for oo, which might appear many times
Dear group,
I recently spent some time debugging something which was producing an
expression involving k*zoo.
Eventually I used help on zoo and discovered it meant complex infinity!
k/0
gives
k*zoo
Wouldn't it be more helpful to spell this out as k*ComplexInfinity?
Maybe oo could be
Hi all
```
n = Symbol('n', finite=True, real=True)
zoo/n# should not this be simplified to zoo
zoo/n
zoo.is_finite
False
(zoo/n).is_finite
```
Same happens for `oo` .
I am not sure why this is so ?. Is this is a bug ?
Gaurav Dhingra
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I'd say it shouldn't simplify automatically. Automatic simplifications
based on assumptions are what makes the core slow.
That isn't to say that simplify(zoo/n) shouldn't do something, however.
Aaron Meurer
On Mon, Jun 15, 2015 at 8:56 AM, Gaurav Dhingra axyd0...@gmail.com wrote:
Hi all
```
On Monday, 8 June 2015 22:18:09 UTC+2, Aaron Meurer wrote:
My guess is that limit() doesn't look at assumptions. Also, limit
uses real limits, not complex limits (which are much harder to work
with algorithmically).
Apparently not even Mathematica implements complex limits:
In[1]:=
Are you sure that SymPy's behaviour is well-defined?
In [1]: z = Symbol('z', imaginary=True)
In [2]: z.is_imaginary
Out[2]: True
In [3]: z.is_real
Out[3]: False
In [4]: limit(1/z, z, 0)
Out[4]: ∞
In [5]: type(_)
Out[5]: sympy.core.numbers.Infinity
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My guess is that limit() doesn't look at assumptions. Also, limit
uses real limits, not complex limits (which are much harder to work
with algorithmically).
The oo**zoo thing is a bug. Please open an issue in the issue tracker about it.
Aaron Meurer
On Mon, Jun 8, 2015 at 1:10 PM, Francesco
On Sunday, June 7, 2015 at 2:52:52 PM UTC+3, Paul Royik wrote:
Why 1/0 is complex infinity and log(0) is complex infinity?
They are shorthand notations for the limits of 1/z and log(z) as z
tends to 0. The default domain in SymPy is the complex field, so the
limits are computed in a
Thank you.
How to make it work in real field?
On Monday, June 8, 2015 at 12:05:24 PM UTC+3, Kalevi Suominen wrote:
On Sunday, June 7, 2015 at 2:52:52 PM UTC+3, Paul Royik wrote:
Why 1/0 is complex infinity and log(0) is complex infinity?
They are shorthand notations for the limits of 1/z
Why 1/0 is complex infinity and log(0) is complex infinity?
I also found a bug with oo**zoo. It is recursion error.
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I know this is not very helpful, but I am fairly certain we discussed
this kind of subject, about two years ago, but never really reached a
conclusion. The point is that of cours zoo+zoo should be nan (whereas it
seems like zoo*zoo need not be, but perhaps that was never fixed).
Tom
On
Updates:
Status: Fixed
Comment #8 on issue 3106 by asmeu...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
This was merged.
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Comment #5 on issue 3106 by unlimite...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
https://github.com/sympy/sympy/pull/1096
However, zoo + zoo is still NaN. Do I fix that one as well?
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Comment #6 on issue 3106 by asmeu...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
I'm not sure about that one. If the infinities in the complex plane are
opposite each other across 0, they could cancel (similar to oo - oo).
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Comment #4 on issue 3106 by asmeu...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
That is to say, what you think they should be is wrong. 0 + 0*I should be
0, which is not the same as zoo. -zoo == zoo (because it represents *all*
points at infinity in the
Comment #2 on issue 3106 by hector1...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
While someone is at it, there are few more things which needs to be fixed
In [24]: zoo == z/0
Out[24]: False
In [25]: zoo == 0 + 0*I
Out[25]: False
In [27]: z - zoo
Out[27]:
Comment #3 on issue 3106 by asmeu...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
For the first one, see issue 2096. The rest are correctly implemented.
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Updates:
Labels: EasyToFix
Comment #1 on issue 3106 by asmeu...@gmail.com: zoo*zoo == nan
http://code.google.com/p/sympy/issues/detail?id=3106
(No comment was entered for this change.)
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To
Am 25.02.2012 23:23, schrieb Aaron Meurer:
Yes, I believe it should. That's why I'm wondering why it gives nan.
Same here.
My intuition tells me that whatever path you take for
lim re,im-oo: re+i*im
you get zoo.
Wikipedia says that zoo*zoo is commonly defined as zoo.
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I've created http://code.google.com/p/sympy/issues/detail?id=3106 for
this. It should be easy to fix.
Aaron Meurer
On Sun, Feb 26, 2012 at 6:11 AM, Joachim Durchholz j...@durchholz.org wrote:
Am 25.02.2012 23:23, schrieb Aaron Meurer:
Yes, I believe it should. That's why I'm wondering why
Why is zoo*zoo nan?
In [71]: zoo*zoo
Out[71]: nan
It seems to me that the result should just be zoo.
Aaron Meurer
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what is zoo anyway - I was not able to find anything - even on google
-Sebastian
PS: sorry for beeing OT
On Sat, Feb 25, 2012 at 10:16 AM, Aaron Meurer asmeu...@gmail.com wrote:
Why is zoo*zoo nan?
In [71]: zoo*zoo
Out[71]: nan
It seems to me that the result should just be zoo.
zoo is complex infinity (i.e., S.ComplexInfinity). See
http://en.wikipedia.org/wiki/One_point_compactification and
http://en.wikipedia.org/wiki/Riemann_sphere. If you think of oo
(infinity) as the limit of arbitrarily large real numbers, you can
think of zoo as the limit of complex numbers with
In that case, zoo*zoo is zoo. No ?
Christophe BAL
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For more
Yes, I believe it should. That's why I'm wondering why it gives nan.
Aaron Meurer
On Sat, Feb 25, 2012 at 5:45 AM, Christophe BAL projet...@gmail.com wrote:
In that case, zoo*zoo is zoo. No ?
Christophe BAL
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Aaron S. Meurer wrote:
There seem to be a lot of unrelated changes in the pull. Which
commits specifically are you referring to?
3c471f8 2111: log, tan and cot return zoo; zoo+b and zoo*b - zo
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