A condition for the nonsymmetric saddle point matrix being diagonalizable and having real and positive eigenvalues (Q939501)

The authors consider nonsymmetric saddle point matrices of the form \(M = [A B^T; -B C ]\), where \(A\) is symmetric and positive definite, \(B\) is full rank and \(C\) is symmetric and positive semidefinite. For such systems they provide a new sufficient condition such that \(M\) is diagonalizable, with real positive eigenvalues.