EISPACK is a software library for numerical computation of eigenvalues and eigenvectors of matrices, written in FORTRAN.
In addition, it includes subroutines to perform a singular value decomposition.
The library drew heavily on algorithms developed by James Wilkinson, which were originally implemented in ALGOL.
Brian Smith led a team at Argonne developing EISPACK, initially by translating these algorithms into FORTRAN.
Jack Dongarra joined the team as an undergraduate intern at Argonne, and later went on to create LAPACK, which has largely superseded EISPACK and LINPACK.