Can math.atan2 return INF?

Steven D'Aprano steve+comp.lang.python at pearwood.info
Tue Jun 28 02:27:37 EDT 2016


On Tuesday 28 June 2016 16:12, Gregory Ewing wrote:

> Rustom Mody wrote:
>> I said that for the Haskell list [0..]
>> 
>> [0..] ++ [-1] == [0..]
>> 
>> He said (in effect) yes that -1 would not be detectable but its still there!
> 
> The code to generate it is there, but it will never
> be executed, so the compiler is entitled to optimise
> it away. :-)
> 
> He may have a point though. There are avenues of
> mathematics where people think about objects such
> as "all the natural numbers, followed by -42", and
> consider that to be something different from just
> "all the natural numbers".
> 
> So, a mathematician would probably say they're not
> equal. A scientist would say they may or may not be
> equal, but the difference is not testable.
> 
> An engineer would say "Lessee, 0, 1, 2, 3, 4, 5,
> 6, 7... yep, they're equal to within measurement
> error."

And a programmer would write a script to compare the two, and then go to 
Stackoverflow asking for help to optimize it because it takes too long to 
complete.

Relevant:

https://blogs.msdn.microsoft.com/oldnewthing/20131029-00/?p=2803




-- 
Steve



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