# Interface Schur complement preconditioning for piece wise orthotropic discretizations with high aspect ratios

The main problem in designing the algorithm is the interface Schur complement preconditioning, which is closely related to obtaining boundary norms for discrete harmonic functions on the shape irregular domains. The computational cost of the designed Schur complement algorithm is $O(N (log N)^{1/2}$ arithmetic operations, where N is the number of unknowns. The DD algorithm, incorporating the suggested Schur complement preconditioner, requires the same arithmetical work.