## Version 1.1.0

This subroutine uses the Lanczos algorithm to compute the part of the spectrum of a large symmetric matrix A that lies in a speciﬁed interval, that is, it computes eigenvalues without regard to multiplicities. The user need only provide $A$ in the form of code which computes $u+Av$ for any given vectors $u$ and $v$. Auxiliary calls allow corresponding eigenvectors to be found.