#10058: Segfault in backward and inverse FFT for 2**n elements
----------------------------------------------------------+-----------------
Reporter: mpatel | Owner:
jason, jkantor
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-5.8
Component: numerical | Resolution:
Keywords: gsl, fft, segfault | Work issues:
Report Upstream: N/A | Reviewers:
Luis Felipe Tabera Alonso
Authors: Mike Hansen, Luis Felipe Tabera Alonso | Merged in:
Dependencies: | Stopgaps:
----------------------------------------------------------+-----------------
Changes (by {'newvalue': u'Mike Hansen, Luis Felipe Tabera Alonso', 'oldvalue':
''}):
* keywords: => gsl, fft, segfault
* reviewer: => Luis Felipe Tabera Alonso
* status: new => needs_review
* author: => Mike Hansen, Luis Felipe Tabera Alonso
Old description:
> Sage crashes when asked to do a backward or inverse FFT for sizes that
> are powers of two:
> {{{
> sage: a = FFT(5)
> sage: a[1] = 2
> sage: a.forward_transform()
> sage: a.backward_transform()
> sage: a = FFT(4)
> sage: a[1] = 2
> sage: a.forward_transform()
> sage: a.backward_transform()
>
> ------------------------------------------------------------
> 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).
> ------------------------------------------------------------
> }}}
> This is with 4.6.alpha2.
>
> Joal Heagney reported this problem on [http://groups.google.com/group
> /sage-devel/browse_thread/thread/7830e0c484a0f38d sage-devel].
New description:
Sage crashes when asked to do a backward or inverse FFT for sizes that are
powers of two:
{{{
sage: a = FFT(5)
sage: a[1] = 2
sage: a.forward_transform()
sage: a.backward_transform()
sage: a = FFT(4)
sage: a[1] = 2
sage: a.forward_transform()
sage: a.backward_transform()
------------------------------------------------------------
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).
------------------------------------------------------------
}}}
This is with 4.6.alpha2.
Joal Heagney reported this problem on [http://groups.google.com/group
/sage-devel/browse_thread/thread/7830e0c484a0f38d sage-devel].
Apply: trac_10058.2.patch, trac_10058_doc.patch
--
Comment:
I have reviewed (and rebased) the code of M. Hansen and it is correct. I
have also added another patch that fills coverage of fft.pyx and cleans
the plot code. This second patch needs review.
Apply: trac_10058.2.patch, trac_10058_doc.patch
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10058#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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