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Nov 11, 2010, 11:20:51 AM11/11/10

to sage-...@googlegroups.com

One of my interacts for class is segfaulting in 4.6, but worked fine in

4.5.2. The problem is illustrated below:

4.5.2. The problem is illustrated below:

sage: V=(QQ^2).span_of_basis([[1,1]])

sage: v=V([1,1])

sage: x=sqrt(2)*v

sage: 3*x

------------------------------------------------------------

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).

------------------------------------------------------------

I'm trying to track this down at

http://trac.sagemath.org/sage_trac/ticket/10250, and it seems to involve

pynac and the coercion system. Does anyone have alpha versions of 4.6

(or 4.5.3, for that matter) that they can test the above code in so we

can try to pinpoint what change caused the problem? The code above

doesn't work for my copy of 4.6alpha3, for example.

Thanks,

Jason

Nov 11, 2010, 11:32:28 AM11/11/10

to sage-devel

On Nov 11, 8:20 am, Jason Grout <jason-s...@creativetrax.com> wrote:

> One of my interacts for class is segfaulting in 4.6, but worked fine in

> 4.5.2. The problem is illustrated below:

>

> sage: V=(QQ^2).span_of_basis([[1,1]])

> sage: v=V([1,1])

> sage: x=sqrt(2)*v

> sage: 3*x

>

> ------------------------------------------------------------

> 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).

> ------------------------------------------------------------

>

> I'm trying to track this down athttp://trac.sagemath.org/sage_trac/ticket/10250, and it seems to involve
> One of my interacts for class is segfaulting in 4.6, but worked fine in

> 4.5.2. The problem is illustrated below:

>

> sage: V=(QQ^2).span_of_basis([[1,1]])

> sage: v=V([1,1])

> sage: x=sqrt(2)*v

> sage: 3*x

>

> ------------------------------------------------------------

> 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).

> ------------------------------------------------------------

>

> pynac and the coercion system. Does anyone have alpha versions of 4.6

> (or 4.5.3, for that matter) that they can test the above code in so we

> can try to pinpoint what change caused the problem? The code above

> doesn't work for my copy of 4.6alpha3, for example.

I have 4.5.3 on both a Mac (OS X 10.6) and on sage.math, and on both,
> (or 4.5.3, for that matter) that they can test the above code in so we

> can try to pinpoint what change caused the problem? The code above

> doesn't work for my copy of 4.6alpha3, for example.

your example works fine. I have 4.6.alpha1 on the same Mac, and I get

the segfault. (I also have 4.6.alpha2 on an OpenSolaris machine, and

that also segfaults.)

--

John

Nov 11, 2010, 12:14:55 PM11/11/10

to sage-...@googlegroups.com

Thanks! That helped tremendously. Now it seems like the problem may

have been introduced in http://trac.sagemath.org/sage_trac/ticket/9502

I'll keep testing...

Thanks,

Jason

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