#19016: Better hash for Element
-------------------------------------+-------------------------------------
Reporter: ncohen | Owner:
Type: defect | Status: needs_work
Priority: critical | Milestone: sage-6.10
Component: misc | Resolution:
Keywords: | Merged in:
Authors: Nils Bruin, | Reviewers:
Vincent Delecroix | Work issues:
Report Upstream: N/A | Commit:
Branch: public/19016-bis | d34e7c3dfcda5b31ea4b5f1d112d843ae0d0e549
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Changes (by jdemeyer):
* status: needs_review => needs_work
Comment:
1. In `src/sage/rings/polynomial/laurent_polynomial.pyx`, the function
`__hash__` is defined twice in the same class.
2. This isn't proper doctest syntax:
{{{
#!diff
+ def __hash__(self):
+ """
+ TESTS:
+
+ It would be nice if the following would produce a list of
+ 15 distinct hashes.
+
+ sage: K.<t> = FunctionField(QQ)
+ sage: len({hash(t^i+t^j) for i in [-2..2] for j in [i..2]})
+ 10
+ """
+ return hash(self._x)
}}}
3. Could you justify the need to add lots of comparison functions?
4. Why is this needed?
{{{
#!diff
- return self.element_class(self, m)
+ return self.element_class(self, ZZ(m))
}}}
5. This looks very suspicious:
{{{
[ 0 1]
[-272118 0]
- sage: a.matrix() * b
+ sage: a.matrix() * b.matrix()
[-272118 0]
[ 0 -462]
- sage: a * b.matrix()
+ sage: a.matrix() * b.matrix()
[-272118 0]
[ 0 -462]
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/19016#comment:97>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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