We study three computer algebra systems, namely SageMath (with SageManifolds
package), Maxima (with ctensor package) and Python language (with GraviPy
module), which allow tensor manipulation for general relativity calculations
along with general algebraic calculations. We present a benchmark of these
systems using simple examples. After the general analysis, we focus on the
SageMath and SageManifolds system to derive, analyze and visualize the
solutions of the massless Klein-Gordon equation and geodesic motion with
Hamilton-Jacobi formalism. We compare our numerical result of the Klein-Gordon
equation with the asymptotic form of the analytical solution to see that they
agree.Comment: 21 pages, 4 figures. Updated to match the published versio