comments and questions
- To: mathgroup at smc.vnet.net
- Subject: [mg35280] comments and questions
- From: "Stanislaw Ewert-Krzemieniewski" <ewert at arcadia.tuniv.szczecin.pl>
- Date: Sat, 6 Jul 2002 05:44:24 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Dear Sirs,
I have the following permanent problems with MathTensor:
1) Running Mathematica 4.1 AddIndexTypes does not work.
2) Running Mathematica 2.2.3 DefineTensor[ T, {{1,2}, 1}] yields
something like
PermWeight :: def: Object T defined
Get::noopen: Can't open /t549559
and T[li,lj] does not look like a tensor component.
Messages of such type (i.e. Can't open ........ ) appear after some
other commands.
There are no such problems when running Mathematica 2.2.1. DOS version.
I have also found three things which look like errors:
1) When Rcsign = -1 (like Eisenhart) the Weyl conformal curvature
tensor is not defined properly.
MapAll[ Simplify , Metricg[uh,uk] ( WeylC[lh,li,lj,lk] /.
WeylToRiemannRule) //CanAll // Tsimplify]
does not give 0.
2) SameQ[ RiemannR[la,lb,la,ld], RiemannR[la,ld,la,lb] ] gives False.
One more condition should be added in definition.
3) Metricg[uh,uk] TraceFree RicciR[lh,lk] // CanAll // Tsimplify does
not vanish.
Yours faithfully
Stanislaw Ewert-Krzemieniewski