| Functionality
| This package is a preconditioned conjugate gradient method for
eigenproblems (symmetric positive in version 4).
Main features
- a matrix-free iterative method for computing several extreme eigenpairs of symmetric positive (generalized - coming soon!) eigenproblems
- a user-defined symmetric positive preconditioner (a good preconditioner for a stiffness matrix works well for the corresponding eigenvalue problem, too!)
- robustness with respect to random initial approximations, variable preconditioners, and ill-conditioning (up to 10^16) of the stiffness matrix
- apparently optimal convergence speed
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