Link with sci-libs/arpack libraries for eigen decomposition

Packages describing “arpack” as local USE flag

Package “arpack” Flag Description
sci-libs/armadillo Link with sci-libs/arpack libraries for eigen decomposition
sci-mathematics/slepc Adds support for ARPACK (sci-libs/arpack)
sci-libs/dealii Adds support for ARPACK (sci-libs/arpack)

All packages providing a “arpack” USE flag (3)