On Wednesday 10 September 2008, John Cremona wrote:
> 2008/9/10 Nick Alexander <[EMAIL PROTECTED]>:
> > On 10-Sep-08, at 1:49 AM, Martin Albrecht wrote:
> >> On Wednesday 10 September 2008, mabshoff wrote:
> >>> This is double plus not good.
> >>>
> >>> {{{
> >>> sage: GF(109)['x', 'y'](-10)
> >>> -10
> >>> sage: GF(109)['x'](-10)
> >>> 99
> >>>
> >>> }}}
> >>
> >> I don't see the problem, since -10 == 99 mod GF(109).Even if it is
> >> undesired
> >> that they print differently how come it is 'major'?
> >
> > Okay, maybe it is not major. For internal reasons, I am very
> > unsettled to get back different representations for the same thing.
> > Try:
> >
> > {{{
> > sage: GF(109)['x', 'y'](-10)
> > -10
> > sage: GF(109)['x', 'y'](-10).constant_coefficient()
> > 99
> > }}}
> >
> > I can't see how this won't bite someone in the ass sometime.
>
> Maybe. As far as I can see the _repr_() function on the (constant)
> poly just gets a string from singular, so is relying on singular's
> representation for integers mod 109. While the constant_coefficient()
> function is returning a Sage object. There does not seem to be a
> method for turning the singular form into a Sage polynomial.
Of course, I *could* write our own _repr_ function instead of just using
whatever Singular returns back.
Martin
--
name: Martin Albrecht
_pgp: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99
_www: http://www.informatik.uni-bremen.de/~malb
_jab: [EMAIL PROTECTED]
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