On Sep 15, 10:26 am, Martin Albrecht <[EMAIL PROTECTED]>
wrote:
> On Monday 15 September 2008, phil wrote:
>
> > I've been pushing the limits of determinant calculation over
> > multivariate polynomial rings. I can calculate determinants of
> > matrices up to 9x9 of the form [[x_0_0, x_0_1],[x_1_0, x_1_1]] (each
> > element is a single unique variable). When I get to 10x10 is runs for
> > a while the crashes with:
> > Unhandled SIGSEGV: A segmentation fault occured in SAGE.
> > This probably occured 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'll try to reproduce the crash and see what I can do about it. You could help
> by running sage -gdb (if you have gdb installed) and send me the backtrace
> off list. Thanks.
>
The original machine I was using was needed for other things. So, I
ran it on sage 3.1.2rc4 on sage.math.washington.edu and it completed
successfully after 169446 seconds. So, the problem was specific to
the setup I was using or it was fixed in 3.1.2rc4.
The scaling of the problem seems worse than it should be though.
The 9x9 problem takes 40 seconds while the 10x0 problem takes 4236
times longer. That's worse than O(n!) let along O(n^3).
If your curious, the test problem is at
http://sage.math.washington.edu/home/fongpwf/sage_work/determinant_10_poly.sage
Phil
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