1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* CTENSOR features for (mainly) gravitational theory
*/
if get('ctensor,'version)=false then load(ctensor);
("A conformally flat metric helps demonstrate the curvature tensors")$
(ratwtlvl:false,ratfac:true);
derivabbrev:true;
dim:4;
ct_coords:[x,y,z,t];
lg:a*ident(4);
dependencies(a(t));
("cmetric() computes the metric inverse:")$
cmetric();
ug;
("christof() computes the Christoffel-symbols of the 1st and 2nd kind")$
christof(mcs);
("ricci() computes and optionally displays the covariant Ricci tensor")$
ricci(true);
("uricci() computes the mixed-index Ricci tensor")$
uricci(true);
("riemann() computes the (3,1) Riemann-tensor")$
riemann(true);
("The covariant Riemann-tensor is obtained with lriemann()")$
lriemann(true);
("While uriemann() computes the contravariant Riemann tensor")$
uriemann(true);
("The mixed-index Einstein tensor is computed by einstein()")$
einstein(true);
("The covariant Einstein tensor is computed by leinstein()")$
leinstein(true);
("Rinvariant obtains the Kretchmann-invariant:")$
rinvariant();
("The Weyl tensor is empty for a conformally metric")$
weyl(true);
/* End of demo -- comment line needed by MAXIMA to resume demo menu */
|
