libarpack2 binary package in Ubuntu Focal amd64

 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.
 .
 Important Features:
 .
  * Reverse Communication Interface.
  * Single and Double Precision Real Arithmetic Versions for Symmetric,
    Non-symmetric,
  * Standard or Generalized Problems.
  * Single and Double Precision Complex Arithmetic Versions for Standard or
    Generalized Problems.
  * Routines for Banded Matrices - Standard or Generalized Problems.
  * Routines for The Singular Value Decomposition.
  * Example driver routines that may be used as templates to implement
    numerous Shift-Invert strategies for all problem types, data types and
    precision.
 .
 This package contains the shared library.

Source package