[sage-devel] segfault when multiplying QQ constant and SR vector (with user basis)

[Jason Grout]

This code worked in Sage 4.5.2.  I just realized that it now gives a 
segfault in 4.6.  Does anyone know what is going on?

sage: A=matrix(QQ, [[2,1],[0,3]])
sage: eval, evecs,mult=A.eigenvectors_right()[0]
sage: evec=evecs[0]
sage: unitevec=evec/evec.norm()
sage: unitevec
(1/2*sqrt(2), 1/2*sqrt(2))
sage: parent(eval)
Rational Field
sage: eval
3

and then:

sage: w=(SR^2)(unitevec)
sage: parent(w) # works fine
Vector space of dimension 2 over Symbolic Ring
sage: eval*w
(3/2*sqrt(2), 3/2*sqrt(2))

but here's the problem:

sage: parent(unitevec) # gives problem
Vector space of degree 2 and dimension 1 over Symbolic Ring
User basis matrix:
[1 1]
sage: eval*unitevec


------------------------------------------------------------
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).
------------------------------------------------------------

Thanks,

Jason

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