#10250: segfault when multiplying QQ constant and SR vector (with user basis)
------------------------------+---------------------------------------------
Reporter: jason | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone:
Component: linear algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by jason):
* cc: craigcitro, robertwb (added)
Comment:
Ccing Robert B and Craig Citro, since it looks like it might be a problem
in the coercion system, and maybe in how the coercion system builds a
module with a user basis:
{{{
sage: V=(QQ^2).span_of_basis([[1,1]])
sage: v=V([1,1])
sage: w=v.change_ring(SR)
sage: w.parent()
Vector space of degree 2 and dimension 1 over Symbolic Ring
User basis matrix:
[1 1]
sage: 3*w
(3, 3)
sage: x=sqrt(2)*v # here the coercion system builds the parent of x
sage: x.parent() is w.parent()
False
sage: x.parent()
Vector space of degree 2 and dimension 1 over Symbolic Ring
User basis matrix:
[1 1]
sage: x.parent() == w.parent() # equivalent parents between x and w
True
sage: 3*x # but we get a segfault when multiplying x by something
------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component
of Sage has a bug in it (typically accessing invalid memory)
or is not properly wrapped with _sig_on, _sig_off.
You might want to run Sage under gdb with 'sage -gdb' to debug this.
Sage will now terminate (sorry).
------------------------------------------------------------
}}}
Also, notice that trying to get the coercion system to explain itself also
segfaults:
{{{
sage: cm = sage.structure.element.get_coercion_model(); cm
<sage.structure.coerce.CoercionModel_cache_maps object at 0x101f3b6b0>
sage: sage: V=(QQ^2).span_of_basis([[1,1]])
sage: v=V([1,1])
sage: x=sqrt(2)*v
sage: cm.explain(3.parent(), x.parent())
------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component
of Sage has a bug in it (typically accessing invalid memory)
or is not properly wrapped with _sig_on, _sig_off.
You might want to run Sage under gdb with 'sage -gdb' to debug this.
Sage will now terminate (sorry).
------------------------------------------------------------
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10250#comment:4>
Sage <http://www.sagemath.org>
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