Against PEP 240

David C. Ullrich ullrich at math.okstate.edu
Fri Jun 1 16:43:24 CEST 2001


On Thu, 31 May 2001 21:07:26 -0400, "Tim Peters" <tim.one at home.com>
wrote:

>[Tim]
>> Jurjen N.E. Bos contributed a Python implementation of the constructive
>> reals several years ago. ...
>
>[David C. Ullrich]
>> Really? You don't happen to recall where I can find this, do you?
>>
>> (Um: or are you referring to the celebrated real.py?
>
>Right.
>
>> At least in the version of real.py I have the reals have arbitrary
>> but predetermined finite precision. If that's what you meant never mind.
>
>You have to represent reals as string-form function evaluations, then hook
>into the machinery that re-evaluates them with ever-increasing precision.
>It's barely documented and difficult to reverse-engineer.  The only "out of
>the box" way to do it is via the interactive functions that keep printing
>more and more digits until you interrupt them.  It's not enough *just* to
>use the Real class. 

Yeah, I figured later that I'd thought you were saying more than
you actually said here.

> If I ever get a free month, I'd like to package that
>machinery for non-interactive demand-driven use via a new class (which I
>expect is more what you have in mind).

Yup. (Don't get the idea I was or am requesting anything here, it's
certainly not something I need. Was just curious whether you were
talking about new Bos stuff I hadn't heard of. The idea of _reals_
with actual infinite precision is fascinating, but at least
from my point of view that's all it is.)

>> Those wacky reals. Makes you wonder how they got the name.
>
>Probably some Dutch guy; heck, they even name languages after snakes.

I didn't know that, thanks.


David C. Ullrich
*********************
"Sometimes you can have access violations all the 
time and the program still works." (Michael Caracena, 
comp.lang.pascal.delphi.misc 5/1/01)



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