The modified Uzawa methods for solving singular linear systems

For nonsingular linear systems, Yunin 2013 studied three variants of the Uzawa method; see Yun (2013) [18]. These methods contain the Uzawa-AOR method and the Uzawa-SAOR method as special cases. On the basis of the Uzawa-AOR method and the Uzawa-SAOR method, Liin 2017 proposed two modified Uzawa methods by constructing the coefficient matrix of AOR method into a new form of the product of lower triangular matrix and upper triangular matrix; see Li (2017) [26]. In this paper, we present two modified Uzawa methods for solving singular linear systems. The semi-convergence of these methods is analyzed by using the techniques of singular value decomposition and Moore-Penrose inverse. The numerical results are used to verify the theoretical results.