#8800: Doctest coverage of categories
--------------------------+-------------------------------------------------
Reporter: SimonKing | Owner: Simon King
Type: defect | Status: new
Priority: major | Milestone: sage-4.4.2
Component: categories | Keywords: categories doctests
Author: Simon King | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by SimonKing):
I believe that free modules of the same rank but with different inner
product matrix should not allow coercion. Hence, I think the following is
a bug:
{{{
sage: P.<t> = ZZ[]
sage: M1 = FreeModule(P,3)
sage: M2 = QQ^3
sage: M2([1,1/2,1/3]) + M1([t,t^2+t,3]) # This is ok
(t + 1, t^2 + t + 1/2, 10/3)
sage: M3 = FreeModule(P,3, inner_product_matrix = Matrix(3,3,range(9)))
sage: M2([1,1/2,1/3]) + M3([t,t^2+t,3]) # This should result in an
error
(t + 1, t^2 + t + 1/2, 10/3)
}}}
This inappropriate coercion can be avoided by modifying the merge method
of the construction functors, so that the inner product matrices are used
for comparison as well.
But I acknowledge that other people might think that a coercion should
exist. Perhaps I shall ask on sage-algebra...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8800#comment:22>
Sage <http://www.sagemath.org>
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