#19044: Span of trivial cones
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Reporter: mjo | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.9
Component: geometry | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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The following has been annoying me in my doctests. We can take the span of
most cones:
{{{
sage: K = Cone([(1,)])
sage: span(K)
Free module of degree 1 and rank 1 over Integer Ring
Echelon basis matrix:
[1]
sage: span(K, K.lattice().base_ring())
Sublattice <N(1)>
}}}
But `span()` tries to deduce the base ring itself, and that doesn't work
for the trivial cone:
{{{
sage: K = Cone([], ToricLattice(0))
sage: span(K)
...
AttributeError: 'Objects_with_category' object has no attribute
'base_ring'
}}}
I've worked around it by implementing `span` as a method on
`IntegralRayCollection`:
{{{
def span(self):
return span(self, self.lattice().base_ring())
}}}
Does this approach sound good, or should it be fixed with a special case
inside `span()`?
--
Ticket URL: <http://trac.sagemath.org/ticket/19044>
Sage <http://www.sagemath.org>
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