forwarded 191671 maxima@www.ma.utexas.edu
thanks
Greetings! This bug has been filed by a Debian maxima user and looks
to be an issue with maxima proper. I'm away from my email until 6/1,
and cannot receive sourceforge mail as my ISP blocks it as spam. I
therefore cannot usefully register the bug on the website. Please
excuse therefore the submission to this list instead.
Package: maxima
Version: 5.9.0-10
The output of computing the Weyl tensor on an arbitrary 3 metric says
that the spacetime is conformally flat. The vanishing of the Weyl
tensor implying conformal flatness is only true in dimensions >= 4, and
the Weyl tensor is automatically zero in dimension 3. A more complete
discussion may be found in the book
Lovelock, D. and Rund, H., Tensors, Differential forms and Variational
principles, John Wiley, 1975. pages 292-293 esp 7.32 and 7.34.
Sample output:
--------------------------------------------------------------------------------
bates@tiki:~$ maxima
GCL (GNU Common Lisp) (2.5.2) Thu Mar 20 10:36:35 EST 2003
Licensed under GNU Library General Public License
Dedicated to the memory of W. Schelter
Use (help) to get some basic information on how to use GCL.
Maxima 5.9.0 http://maxima.sourceforge.net
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
This is a development version of Maxima. The function bug_report()
provides bug reporting information.
(C1) load(ctensr);
(D1) /usr/share/maxima/5.9.0/share/tensor/ctensr.mac
(C2) g=tsetup();
enter the dimension of the coordinate system:
3;
do you wish to change the coordinate names?
n;
do you want to
1. enter a new metric?
2. enter a metric from a file?
3. approximate a metric with a taylor series?
1;
Is the matrix 1. Diagonal 2. Symmetric 3. Antisymmetric 4. General
Answer 1, 2, 3 or 4 : 1;
Row 1 Column 1: x;
Row 2 Column 2: y;
Row 3 Column 3: z;
Matrix entered.
enter functional dependencies with the depends function or 'n' if none
n;
do you wish to see the metric?
y;
[ x 0 0 ]
[ ]
[ 0 y 0 ]
[ ]
[ 0 0 z ]
do you wish to see the metric inverse?
n;
(D2) g = DONE
(C3) weyl(g);
this spacetime is conformally flat
(D3) DONE
(C4)
-----------------------------------------------------------------------------------
On a related note, xmaxima does not respond to the tsetup(); command, it
never responds with the line
enter the dimension of the coordinate system:
Cheers,
Larry Bates