#11779: python ints vs sage ints with respect to powers weirdness
-----------------------------+----------------------------------------------
Reporter: dimpase | Owner: AlexGhitza
Type: defect | Status: positive_review
Priority: major | Milestone: sage-4.7.2
Component: coercion | Keywords:
Work_issues: | Upstream: N/A
Reviewer: William Stein | Author: Dmitrii Pasechnik
Merged: | Dependencies:
-----------------------------+----------------------------------------------
Changes (by leif):
* reviewer: => William Stein
Old description:
> {{{
> print type(int(3) + 3)
> print type(int(3) * 3)
> print type(3 ^ int(3))
> print type(int(3) ^ 3)
> }}}
> first three are Sage Integers but last one is just a Python int.
> Worse still:
> {{{
> sage: int(3)^-3
> 0.037037037037037035
> sage: type(int(3)^-3)
> <type 'float'>
> sage: int(3)^QQ(-3)
> 1/27
> sage: type(int(3)^QQ(-3))
> <type 'sage.rings.rational.Rational'>
> }}}
> is very inconsistent, as well as leads to loss of precision, even though
> it can be
> avoided. As well as
> {{{
> sage: p(x)=x^-3
> sage: p(int(3))
> 1/27
> }}}
> is not consistent.
>
> A patch is at
> http://trac.sagemath.org/sage_trac/attachment/ticket/11779/trac_11779.patch
>
> See https://groups.google.com/d/topic/sage-devel/RG-8xcPF53g/discussion
New description:
{{{
print type(int(3) + 3)
print type(int(3) * 3)
print type(3 ^ int(3))
print type(int(3) ^ 3)
}}}
first three are Sage Integers but last one is just a Python int.
Worse still:
{{{
sage: int(3)^-3
0.037037037037037035
sage: type(int(3)^-3)
<type 'float'>
sage: int(3)^QQ(-3)
1/27
sage: type(int(3)^QQ(-3))
<type 'sage.rings.rational.Rational'>
}}}
is very inconsistent, as well as leads to loss of precision, even though
it can be
avoided. As well as
{{{
sage: p(x)=x^-3
sage: p(int(3))
1/27
}}}
is not consistent.
Apply [attachment:trac_11779.patch] to the Sage library.
See [https://groups.google.com/d/topic/sage-devel/RG-8xcPF53g/discussion].
--
Comment:
Please don't put links to the '''HTML version''' of a patch into the
description.
Trac wiki mark-up is `[attachment:here_comes_the_filename]`.
----
Wonder whether your undergrads will complain that `[1r][0]` (or
`(1r,)[0]`) doesn't yield a Sage `Integer`...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11779#comment:23>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
