2009/4/10 William Stein <wst...@gmail.com>:
>
> On Fri, Apr 10, 2009 at 7:43 AM, John Cremona <john.crem...@gmail.com> wrote:
>>
>> 2009/4/10 William Stein <wst...@gmail.com>:
>>>
>>> On Fri, Apr 10, 2009 at 3:09 AM, John Cremona <john.crem...@gmail.com>
>>> wrote:
>>>>
>>>> For me the trouble with extended_*.py is that I have no idea what they
>>>> aactually are, so it is hard to get started....
>>>
>>> But aren't you just dying to find out what they are? :-)
>>
>> Well... I did not even know that these classes exited until I made
>> the patch at #5685 (still awaiting review) and had to adjust a couple
>> of functions in one of those files. I can guess: it somehow adds
>> +infinity and -infinity to ZZ in a way that makes as much sense as
>> possible.
>>
>> But search_src("ExtendedInteger") only picks up these two files, which
>> suggests to me (maybe wrongly) that they are not actually used
>> anywhere!
>>
>
> They are used. ExtendedInteger is used by the extended_rational_field
> file, and that is used in at least two places:
>
> rings/rational_field.py: sage: E = ExtendedRationalField
> rings/padics/valuation.py:QQe =
> sage.rings.extended_rational_field.ExtendedRationalField
Fair enough, they are used in the padics to hold valuations which can
be infinite. (Though I notice that ZZ(0).valuation(3) is plain old
<class 'sage.rings.infinity.PlusInfinity'>).
Now the padics section is also seriously under-documented. Funny
coincidence, that...
John
>
> William
>
> >
>
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