Abstract. The paper establishes the exact error energy compression ratio on each step of the two-step method, which shows a better convergence rate compared with the one-step method with optimal parameter.
Keywords: iterative methods, convergence rate, energy norm, characteristic equation, energy equivalence constants.
1Taras Shevchenko National University of Kyiv, Kyiv, Ukraine,
e-mail: viktorprikazchikov@gmail.com.
2V. M. Glushkov Institute of Cybernetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine,
e-mail: khimich505@gmail.com.