/* 
 * 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);
("We set up a simple nonempty metric")$
derivabbrev:true;
dim:4;
lg:matrix([a,0,0,0],[0,x^2,0,0],[0,0,x^2*sin(y)^2,0],[0,0,0,-d]);
depends([a,d],x);
ct_coords:[x,y,z,t];
("Compute the inverse metric")$
cmetric();
("Compute the Einstein tensor")$
einstein(false);
("Find a set of unique differential equations in ein")$
findde(ein,2);
("Find out which tensor components were used in these equations")$
deindex;

/* End of demo -- comment line needed by MAXIMA to resume demo menu */