Eigenvalues and 0 mass nodes



Hi

I am using ANSYS to solve for the eigenvalues of an FE model with
nodes with 0 mass (that is solve the generalised eigenvalue problem Kx
= lambdaMx where M has some 0s on the diagonal)

Does anyone know how ansys solves this, i.e. how does ansys or any
other FE program deal with these 0 mass terms?

Regards

Paul
.