I have a large scale system with the following equations of motions
$M\ddot z(t)+K z(t)=F(t)$
$M$ is the mass matrix
$K$ is the stiffness matrix
And I want to solve the equation for displacement $z(t)$, the eigenvalues and the eigenvectors with load dependent Ritz Analysis ( the algorithm is described succinctly in here).
I know that I can use APRACK to for large scale eigenvalue problems, but what about load dependent Ritz Analysis? Is there already a solver ( commercial, open source, all doesn't matter) out there that does this kind of thing?
Just to be clear, I am looking for a programming library that I can use, not a commercial software that I can't call programmatically .