#16127: Fix comparison of PARI objects
-------------------------------------+-------------------------------------
Reporter: pbruin | Owner:
Type: defect | Status: needs_review
Priority: critical | Milestone: sage-6.4
Component: interfaces | Resolution:
Keywords: pari comparison | Merged in:
Authors: Peter Bruin | Reviewers: Jeroen Demeyer
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jdemeyer/ticket/16127 | 12fbcad65c6438fe0495c3b2424468f24b49a9ee
Dependencies: | Stopgaps:
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Comment (by pbruin):
Why do you make `<=` and `>=` return `True` for equal objects? To me it
doesn't make a lot of sense. I can see that you might want that `a == b`
implies `a <= b`, but in my opinion asking whether `a <= b` only makes
sense if `a` and `b` are in some partially ordered set (like the real
numbers with plus and minus infinity).
Neither PARI nor Sage returns true for `[0] <= 0` (while they disagree on
`[0] == 0`):
{{{
gp > [0] <= 0
*** at top-level: [0]<=0
*** ^---
*** _<=_: forbidden comparison t_VEC (1 elts) , t_INT.
gp > [0] == 0
%1 = 1
}}}
{{{
sage: [0] <= 0
False
sage: [0] == 0
False
}}}
Note also the following from the
[https://docs.python.org/2/reference/datamodel.html#special-method-names
Python documentation]: "There are no implied relationships among the
comparison operators. The truth of `x==y` does not imply that `x!=y` is
false." Likewise, I don't think we should insist that the truth of `x==y`
implies that of `x<=y`.
--
Ticket URL: <http://trac.sagemath.org/ticket/16127#comment:18>
Sage <http://www.sagemath.org>
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