`scipy.linalg._flapack:zhbevd`

Summary

Eigenvalues and eigenvectors of a Hermitian band matrix, by divide and conquer (LAPACK zhbevd).

ab : ndarray: The band of the symmetric/Hermitian matrix, shape (kd + 1, n): the order n and the bandwidth kd are both read off ab itself. It is consumed rather than returned. The order must be at least 1: the workspace formulas this routine uses do not cover an empty matrix, and the .pyf rejects it outright.
compute_v : int, optional: If nonzero, eigenvectors are computed and z is sized for them; otherwise z comes back as a 1x1 placeholder. Default is 1.
lower : int, optional: If nonzero, ab holds the lower band; otherwise the upper. Default is 0.
ldab : int, optional: Leading dimension of ab. It must equal ab.shape[0]; the argument exists only because the .pyf exposed it. Default is ab.shape[0].
lrwork : int, optional: Real workspace size, at least 1 + 5n + 2n**2 with eigenvectors and n without. The real flavors have no second workspace and take no lrwork.
liwork : int, optional: Integer workspace size, at least 3 + 5n with eigenvectors and 1 without.
overwrite_ab : int, optional: If nonzero, ab may be overwritten in place -- and it is consumed either way, never returned. Unlike the rest of this module, the default is 1; pass 0 to keep your array intact.

w : ndarray: Eigenvalues in ascending order, length n. Real for every flavor.
z : ndarray: Eigenvectors as columns, when compute_v asked for them.
info : int: 0 on success; if negative, the -info-th argument had an illegal value.