This page contains the following files:
 1. Reference solution - 6th order method from S. Blanes, F. Casas, J. A. Oteo, and J. Ros. The Magnus expansion and some of its applications. Phys. Rep., 470(5-6):151–238, 2009
 2. The file with the results for the reference solution
 3. Programs:
   3.1 Strang splitting
   3.2 The 4th order method from P. Bader, S. Blanes, F. Casas, and N. Kopylov. Novel symplectic integrators for the Klein-Gordon equation with space- and time-dependent mass. J Comput. Appl. Math., 350:130–138, 2019
   3.3 - 3.5 The 1st, 2nd and 3rd order asymptotic method from M. Condon, K. Kropielnicka, K. Lademann, and R. Perczyński. Asymptotic numerical solver for the linear Klein-Gordon equation with space- and time-dependent mass. Applied Math. Lett., 115:106935, 2021
   3.6 Xi^3 method from Kropielnicka, K. and Lademann, K. Third order, uniform in low to high oscillatory coefficients, exponential integrators for Klein-Gordon equations. arXiv
   3.7, 3.8 Gamma_1, Gamma_2 methods from the work of K. Kropielnicka, K. Lademann, and Katharina Schratz. Effective highly accurate integrators for linear Klein-Gordon equations from low to high frequency regimes, arXiv