Complex-extrapolated MHSS iteration method for singular complex symmetric linear systems (Q1689454)

To solve a complex system \(Ax=b\), with singular \(A\), the authors start from the modified Hermitian-skew Hermitian splitting (MHSS) algorithm of \textit{Z.-Z. Bai} et al. [Computing 87, No. 3--4, 93--111 (2010; Zbl 1210.65074)]. The modification adds an extra parameter \(\alpha\) to allow for a more general splitting of \(A\). Here a second relaxation parameter \(\omega\in\mathbb{C}\) is introduced to obtain an extrapolation. Conditions for \(\omega\) are derived to guarantee semi-convergence of the method and its theoretically optimal choice is presented.