accelerated normal and skew-hermitian splitting methods for positive definite linear systems

for solving large sparse non-hermitian positive definite linear equations, bai et al. proposed the hermitian and skew-hermitian splitting methods (hss). they recently generalized this technique to the normal and skew-hermitian splitting methods (nss). in this paper, we present an accelerated normal and skew-hermitian splitting methods (anss) which involve two parameters for the nss iteration. we theoretically study the convergence properties of the anss method. moreover, the contraction factor of the anss iteration is derived. numerical examples illustrating the effectiveness of anss iteration are presented.