> [...]
>
> > This looks like an after-effect of ticket #6441. Sebastian Pancratz
> > wrote some very fast code to compute determinants over general
> > commutative rings, which proceeds by computing the characteristic
> > polynomial first. When doing this for symbolic matrices it needs to
> > choose a variable name that won't conflict with anything, so it uses
> > "A0123456789". This shouldn't leak out into the output, but it looks
> > like it has done here.
>
> Which seems to have been solved in sage 4.2.1 by
>
> changeset: 13301:2c11d19e337f
> user: Mike Hansen <mhan...@gmail.com>
> date: Tue Nov 03 13:45:09 2009 +0700
> summary: Trac #5639: minpoly of symbolic matrices is broken
>
> Can anyone confirm this ?
On linux 64 bits (OpenSuSE):
----------------------------------------------------------------------
| Sage Version 4.2, Release Date: 2009-10-24 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
Loading Sage library. Current Mercurial branch is: combinat
sage: m = matrix(4,4, SR(1))
sage: m[3,3] -= var("t")
sage: m.determinant()
(t - 1)*(A0123456789 - 1)^3
But:
----------------------------------------------------------------------
| Sage Version 4.2.1, Release Date: 2009-11-14 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
Loading Sage library. Current Mercurial branch is: combinat
sage: m = matrix(4,4, SR(1))
sage: m[3,3] -= var("t")
sage: m
[ 1 0 0 0]
[ 0 1 0 0]
[ 0 0 1 0]
[ 0 0 0 -t + 1]
sage: m.determinant()
-t + 1
Cheers,
Florent
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