ARPACK is a collection of Fortran77 subroutines designed to solve large
scale eigenvalue problems.
ARPACK software is capable of solving large scale symmetric,
nonsymmetric, and generalized eigenproblems from significant
application areas. The software is designed to compute a few (k)
eigenvalues with user specified features such as those of largest
real part or largest magnitude. Storage requirements are on the order
of n*k locations. No auxiliary storage is required. A set of Schur
basis vectors for the desired k-dimensional eigen-space is computed
which is numerically orthogonal to working precision. Numerically
accurate eigenvectors are available on request.