Tangential decomposition and its generalization
We present a preconditioner for large systems of linear equations based on the incomplete block decomposition for block-tridiagonal matrices. This method generalizes frequency-filtering method of G. Wittum  and methods developed in [2–4] etc.
1. Wittum G. Filternde Zerlegungen-Schnelle Löser für grosse Gleichungssysteme// Teubner Skripten ...
Optimal parameters and sharp estimates of the convergence rate of the tangent expansion
... sharp estimates of the convergence rate for a broad class of model problems. Numerical results prove that high convergence rate can be achieved by using these values also for the problems with varying coefficients.
Vasilyeva E. A.
incomplete block decomposition, tangential decomposition, preconditioner, matrices