LA_SPEV and LA_SPEVD compute all eigenvalues and, optionally,
all eigenvectors of a real symmetric matrix 
in packed storage.
LA_HPEV and LA_HPEVD compute all eigenvalues and, optionally,
all eigenvectors of a complex Hermitian matrix in packed storage.
LA_SPEVD and LA_HPEVD use a divide and conquer algorithm.
If eigenvectors are desired, they can be much faster than LA_SPEV
and LA_HPEV for large matrices but use more workspace.