On Nov 28, 3:03 pm, "William Stein" <[EMAIL PROTECTED]> wrote:
> On Nov 28, 2007 5:45 AM, mabshoff
>
>
>
> <[EMAIL PROTECTED]> wrote:
>
> > On Nov 28, 2:34 pm, "William Stein" <[EMAIL PROTECTED]> wrote:
> > > On Nov 27, 2007 4:21 PM, mabshoff
>
> > > <[EMAIL PROTECTED]> wrote:
>
> > > > Hello folks,
>
> > > > somewhere since 2.8.3 we introduced a new bug that seems to affect
> > > > computing the power of matrices when the entries are multivariate
> > > > polynomials with rational coefficients:
>
> > > > [EMAIL PROTECTED] sage-2.8.14$ ./sage
> > > > ----------------------------------------------------------------------
> > > > | SAGE Version 2.8.14, Release Date: 2007-11-24 |
> > > > | Type notebook() for the GUI, and license() for information. |
> > > > ----------------------------------------------------------------------
>
> > > > sage: R.<x,y>=MPolynomialRing(QQ,2)
> > > > sage: A = matrix([[Integer(1),x], [y,Integer(1)]])
> > > > sage: A
>
> > > > [1 x]
> > > > [y 1]
> > > > sage: A*A
>
> > > > [x*y + 1 2*x]
> > > > [ 2*y x*y + 1]
> > > > sage: A**2
>
> > > > ------------------------------------------------------------
> > > > 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 cannot replicate this on either sage.math or osx 10.5 intel:
>
> > > [EMAIL PROTECTED]:~$ sage
> > > ----------------------------------------------------------------------
> > > | SAGE Version 2.8.14, Release Date: 2007-11-24 |
> > > | Type notebook() for the GUI, and license() for information. |
> > > ----------------------------------------------------------------------
>
> > > sage: sage: R.<x,y>=MPolynomialRing(QQ,2)
> > > sage: sage: A = matrix([[Integer(1),x], [y,Integer(1)]])
> > > sage: A
>
> > > [1 x]
> > > [y 1]
> > > sage: A*A
>
> > > [x*y + 1 2*x]
> > > [ 2*y x*y + 1]
> > > sage: A**2
>
> > > [x*y + 1 2*x]
> > > [ 2*y x*y + 1]
>
> > > keyah:~ was$ sage
> > > ----------------------------------------------------------------------
> > > | SAGE Version 2.8.14, Release Date: 2007-11-24 |
> > > | Type notebook() for the GUI, and license() for information. |
> > > ----------------------------------------------------------------------
>
> > > sage: sage: R.<x,y>=MPolynomialRing(QQ,2)
> > > sage: sage: A = matrix([[Integer(1),x], [y,Integer(1)]])
> > > sage: A^3
>
> > > [ 3*x*y + 1 x^2*y + 3*x]
> > > [x*y^2 + 3*y 3*x*y + 1]
> > > sage: A^2
>
> > > [x*y + 1 2*x]
> > > [ 2*y x*y + 1]
> > > sage: A
>
> > > [1 x]
> > > [y 1]
> > > sage: A**2
>
> > > [x*y + 1 2*x]
> > > [ 2*y x*y + 1]
>
> > > -----
>
> > > Your subject line suggests maybe this is a solaris-only issue? Is
> > > that the case?
>
> > Yep.
>
> > > If so, what does "sage -gdb" have to say about it?
>
> > I get a pretty bt that point to __cmp__ in libSingular. Notice that it
> > depends on the coefficient ring, i.e. mv polynomials over ZZ are fine,
> > QQ not so much.
>
> That's probably because polynomials over ZZ are still unfortunately *not*
> implemented using libsingular (which is why they are amusing much
> slower in Sage).
Ok, I didn't know that. I did chat with malb in IRC shortly before he
took off to Paris and he will have a look at the libSingular bt once I
post it.
>
> > I am currently building 2.8.14 on Linux PPC under
> > Linux because I suspect endianess issues and I have valgrind there
> > also to investigate.
>
> The problem doesn't occur on OSX powerpc (fermat.math.harvard.edu), which
> is maybe an endian data point.
>
It is more than that. symmetrica fails with Schubert polynomials on
Solaris and just because the code works correctly on OSX doesn't mean
that there isn't something going wrong. I got valgrind on my PPC Linux
box, so it is always worth trying it out :)
> > I am doing "real" work right now, but I should be done with that in
> > 8-10 hours ;). Once I am done I will get back to Sage and open ticket
> > for all the issues I have uncovered during the port. I have 2.8.14 on
> > neron in /tmp. You need to set LD_LIBRRAY_PATH to my 4.2.1-2 gcc to
> > play with it.
>
> > I also createdhttp://wiki.sagemath.org/solaristo keep track of the
> > port.
>
> Excellent.
>
I added some more info there. Feel free to add your own issues ;)
>
>
> > > William
>
> > Cheers,
>
> > Michael
>
> --
> William Stein
Cheers,
Michael
> Associate Professor of Mathematics
> University of Washingtonhttp://wstein.org
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