Preconditioners for regularized saddle point matrices
Owe Axelsson · Journal of Numerical Mathematics · 2011
Saddle point problems with singular or indefinite pivot blockmatrix arise in various applications. In some problems it may be necessary to regularize the corresponding matrix is some way. By straightforward derivations it is shown that use of certain preconditioners on block diagonal and block triangular form can be very efficient, both for the original matrix and for its regularized forms. As the value of regularization parameter increases, the eigenvalues cluster at unity or at just two points on the real line.