**LA_SBEV** and **LA_SBEVD** compute all eigenvalues and, optionally,
all eigenvectors of a real symmetric matrix in band form.

**LA_HBEV** and **LA_HBEVD** compute all eigenvalues and, optionally,
all eigenvectors of a complex Hermitian matrix in band form.

**LA_SBEVD** and **LA_HBEVD** use a divide and conquer algorithm.
They are much faster than **LA_SBEV** and **LA_HBEV** for large matrices
but use more workspace.

Susan Blackford 2001-08-19