#19928: infinities break the hash contract
-----------------------------+------------------------
Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.1
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: #19927 | Stopgaps:
-----------------------------+------------------------
Description changed by rws:
Old description:
> {{{
> sage: hash(-oo)
> -9223372036854775808
> sage: hash(SR(-oo))
> 1390175631
> sage: hash(oo)
> 9223372036854775807
> sage: hash(SR(oo))
> 1577573780
> sage: hash(unsigned_infinity)
> TypeError: <class 'sage.rings.infinity.UnsignedInfinity'> is not hashable
> sage: hash(SR(unsigned_infinity))
> 2904791665
> }}}
New description:
{{{
sage: hash(-oo)
-9223372036854775808
sage: hash(SR(-oo))
1390175631
sage: hash(oo)
9223372036854775807
sage: hash(SR(oo))
1577573780
sage: hash(unsigned_infinity)
9223372036854775806
sage: hash(SR(unsigned_infinity))
2904791665
}}}
The reason is that (at least with `-oo`) in Pynac they can be represented
as an `expair` and such hashes are calculated using
`all^(rest^coeff)^overall_coeff`.
--
--
Ticket URL: <http://trac.sagemath.org/ticket/19928#comment:2>
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 unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
