Modified and updated numerical experiments to "Error analysis of the Strang splitting for the 3D semilinear wave equation with finite-energy data"

This program is intended to reproduce the results from the preprint
"Error analysis of the Strang splitting for the 3D semilinear wave equation with finite-energy data" by Maximilian Ruff

The program is tested with Windows 10 and Python 3.10 and the following version of its modules:

numpy - 1.26.3
matplotlib - 3.5.1
tikzplotlib - 0.10.1

Figure 1:
Run "run_alpha3.py"

Figure 2:
Run "run_alpha4.py"

Figure 3:
Run "run_alpha5.py"

Parts of the code relies on on code written by B. Dörich in https://doi.org/10.5445/IR/1000130189.