#8890: map_support modifies the zero element of a free module!
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Reporter: jbandlow | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone:
Component: algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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{{{
sage: B = CombinatorialFreeModule(ZZ, ['a','b'])
sage: B.an_element().map_support(lambda i: i)
2*B['a'] + 2*B['b']
sage: B.zero()
2*B['a'] + 2*B['b']
}}}
Looking at the code exposes the problem:
{{{
res = self.parent()(0)
z_elt = {}
for m,c in self.monomial_coefficients().iteritems():
z_elt[f(m)] = c
res._monomial_coefficients = z_elt
return res
}}}
We should not change the dictionary of zero!
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8890>
Sage <http://www.sagemath.org>
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