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- AB
- (
*input/output*) **REAL** or **COMPLEX** array,
shape with (**AB**,1) and (**AB**,2) ,
where is the number of subdiagonals or superdiagonals in the
band and is the order of .

On entry, the upper (if **UPLO** = 'U') or lower
(if **UPLO** = 'L') triangle of matrix in band storage.
The diagonals of are stored in the rows of **AB** so
that the column of is
stored in the column of as follows:

On exit, is overwritten by values generated during
the reduction of to a tridiagonal matrix .
If 'U', the first superdiagonal and the diagonal
of are returned in rows and of .
If 'L', the diagonal and first subdiagonal of
are returned in the first two rows of .

- W
- (
*output*) **REAL** array, shape with
(**W**) .

The eigenvalues in ascending order.

- UPLO
*Optional* (*input*) **CHARACTER(LEN=1)**.

Default value: 'U'.

- Z
*Optional* (*output*) **REAL** or **COMPLEX**
square array, shape with (**Z**,1) .

The columns of **Z** contain the orthonormal eigenvectors of
in the order of the eigenvalues.

- INFO
*Optional* (*output*) **INTEGER**.

If is not present and an error occurs, then the
program is terminated with an error message.

**References**: [1] and [17,9,20].

** Next:** Examples
** Up:** Standard Symmetric Eigenvalue Problems
** Previous:** Purpose
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Susan Blackford
2001-08-19