#8986: Add support for convex rational polyhedral cones
----------------------------------+-----------------------------------------
Reporter: novoselt | Owner: mhampton
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.4.4
Component: geometry | Keywords:
Author: Andrey Novoseltsev | Upstream: N/A
Reviewer: Volker Braun | Merged:
Work_issues: |
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Comment(by novoselt):
I have realized that `(1,0,0)` in the examples above is not a vector, but
just a tuple. Then I have done the following test:
{{{
sage: (1,0,0) == vector([1,0,0])
False
sage: vector([1,0,0]) == (1,0,0)
False
sage: vector([1,0,0]) + (1,0,0)
TypeError: unsupported operand parent(s) for '+': 'Ambient free module of
rank 3 over the principal ideal domain Integer Ring' and '<type 'tuple'>'
sage: (1,0,0) + (1,0,0)
(1, 0, 0, 1, 0, 0)
}}}
It is not really an issue of the coercion, it is just not possible to
always use tuples as a replacement for lattice points. We made it,
however, very easy to work with them:
{{{
sage: N(1,0,0) + N(1,0,0)
N(2, 0, 0)
}}}
So I think that equality tests will remain as they are now. Operations
involving "pure" vectors may need more work, perhaps:
{{{
sage: N(1,0,0) + vector((1,0,0))
N(2, 0, 0)
sage: vector((1,0,0)) + N(1,0,0)
(2, 0, 0)
}}}
although this does not bother me too much and I would suggest leaving this
as is until we see where and how it can cause problems. (Making the second
line return `N(2,0,0)` can be a bit tricky.)
Will post a new patch once I figure out how to work with warnings (never
used them before).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8986#comment:13>
Sage <http://www.sagemath.org>
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