On Fri, Apr 10, 2009 at 11:40 AM, John Cremona <john.crem...@gmail.com>wrote:
>
> 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...
:-) There's a patch in trac (#4637) adding documentation to p-adics, and
I'm going to write a bunch of doctests tomorrow.
And yes, I originally wrote Extended Integers and Extended Rationals when I
was writing lazy p-adics. Since lazy p-adics aren't currently in good
enough shape to be turned on, I don't think any part of the sage library
uses Extended Integers or Extended Rationals. Upon further reflection, I'm
not sure I even need them for lazy p-adics. I don't know if it's a good
idea to just get rid of extended integers and rationals or not.
David
>
>
> John
>
>
> >
> > William
> >
> > >
> >
>
> >
>
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