irlba
(Package: irlba) :
Find a few approximate largest singular values and corresponding
The augmented implicitly restarted Lanczos bi-diagonalization (IRLBA) algorithm finds a few approximate largest singular values and corresponding singular vectors of a sparse or dense matrix using a method of Baglama and Reichel. It is a fast and memory-efficient way to compute a partial SVD.
partial_eigen
(Package: irlba) :
Find a few approximate largest eigenvalues and corresponding eigenvectors of a symmetric matrix.
Use partial_eigen to estimate a subset of the largest (most positive) eigenvalues and corresponding eigenvectors of a symmetric dense or sparse real-valued matrix.
providing 
.