='stebz'``).
        An eigenvalue (or cluster) is considered to have converged if it
        lies in an interval of this width. If <= 0. (default),
        the value ``eps*|a|`` is used where eps is the machine precision,
        and ``|a|`` is the 1-norm of the matrix ``a``.
    lapack_driver : str
        LAPACK function to use, can be 'auto', 'stemr', 'stebz',  'sterf',
        or 'stev'. When 'auto' (default), it will use 'stemr' if ``select='a'``
        and 'stebz' otherwise. 'sterf' and 'stev' can only be used when
        ``select='a'``.

    Returns
    -------
    w : (M,) ndarray
        The eigenvalues, in ascending order, each repeated according to its
        multiplicity.

    Raises
    ------
    LinAlgError
        If eigenvalue computation does not converge.

    See Also
    --------
    eigh_tridiagonal : eigenvalues and right eiegenvectors for
        symmetric/Hermitian tridiagonal matrices

    Examples
    --------
    >>> import numpy as np
    >>> from scipy.linalg import eigvalsh_tridiagonal, eigvalsh
    >>> d = 3*np.ones(4)
    >>> e = -1*np.ones(3)
    >>> w = eigvalsh_tridiagonal(d, e)
    >>> A = np.diag(d) + np.diag(e, k=1) + np.diag(e, k=-1)
    >>> w2 = eigvalsh(A)  # Verify with other eigenvalue routines
    >>> np.allclose(w - w2, np.zeros(4))
    True
    T)