#14125: module_morphism is too liberal on inverting
------------------------------+---------------------------------------------
Reporter: darij | Owner: jason, was
Type: defect | Status: new
Priority: minor | Milestone: sage-5.8
Component: linear algebra | Keywords: module morphism, inverse
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Not saying this is an actual issue, since it seems to depend on bad user
input.
Since I don't know how to reliably do function declarations in the
console, I'm making a py file and then importing it:
PY file:
{{{
def diag_func(p):
if len(p)==0: return 1
else: return p[0]
}}}
Console:
{{{
sage: attach ../diagbug.py #file quoted above
sage: X = CombinatorialFreeModule(ZZ, Partitions(), prefix='x'); x =
X.basis();
sage: Y = CombinatorialFreeModule(ZZ, Partitions(), prefix='y'); y =
Y.basis()
sage: xty = X.module_morphism(diagonal=diag_func, codomain=Y)
sage: ytx = ~xty
sage: ytx(y[Partition([3,2,1])])
1/3*x[[3, 2, 1]]
sage: ytx(y[Partition([3,2,1])]).parent()
Free module generated by Partitions over Integer Ring
}}}
Since I'm working over ZZ, I'd have expected the
"ytx(y[Partition([3,2,1])])" to throw an error, but definitely I'd have
expected the parent to not be defined over ZZ.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14125>
Sage <http://www.sagemath.org>
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