On Nov 20, 2007 9:07 PM, mabshoff
<[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > I've been playing with spaces of modular symbols over finite fields, and
> > I ran into two issues that seem to be separate (they're tickets #1231
> > and #1232 now):
> >
> > 1. doing
> >
> > ModularSymbols(1,8,0,GF(3)).simple_factors()
> >
> > gives
> >
> > - ------------------------------------------------------------
> > 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).
> > - ------------------------------------------------------------
>
> While I cannot reproduce this particular problem on sage.math, of the
> other 4 examples you give the first one also segfaults on sage.math
> with 2.8.13.rc1. So I do have something do debug this from. I will see
> if anything pops up with valgrind.
I did once reproduce exactly the above on OS X 10.5 with vanilla 2.8.12,
but couldn't reproduce it again. However, I do get the following sometimes:
rank4:structure was$ sage -gdb
----------------------------------------------------------------------
| SAGE Version 2.8.12, Release Date: 2007-11-06 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
/Users/was/s/local/bin/sage-gdb-pythonstartup
GNU gdb 6.3.50-20050815 (Apple version gdb-768) (Tue Oct 2 04:07:49 UTC 2007)
sage: ModularSymbols(1,8,0,GF(3)).simple_factors()
...
]
/Users/was/s/devel/sage-cremona/sage/structure/coerce.pyx in
sage.structure.coerce.CoercionModel_cache_maps.bin_op_c()
269 pass
270
--> 271 raise TypeError, arith_error_message(x,y,op)
272
273
<type 'exceptions.TypeError'>: unsupported operand parent(s) for '-':
'Full MatrixSpace of 2 by 2 dense matrices over Finite Field of size
3' and '<type 'int'>'
so that is definitely a bug.
Poor modular symbols -- I wrote them 2 years ago, then everything
changed in sage
out from under them...
William
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