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(input/output) REAL array shape $(:)$ with $size$(D) $= n$, where $n$ is the order of $A$.
On entry, the diagonal elements of the matrix $A$.
On exit, the eigenvalues in ascending order.

(input/output) REAL array, shape $(:)$ with $size$(E) $= n$.
On entry, the $n - 1$ subdiagonal elements of $A$ in E$_1$ to E$_{n-1}\,$. ${\bf E}_n$ need not be set but is used by the routine.
On exit, the contents of E are destroyed.

Optional (output) REAL square array, shape$(:,:)$ with $size$(Z,1) $= n$.
The columns of ${\bf Z}$ contain the orthonormal eigenvectors of $A$ in the order of the eigenvalues.

Optional (output) INTEGER.

\item[{$= 0$:}] successful exit.
\item[{$< 0$:}] if {\bf INFO} $...
...FO} $= i$, then $i$\ elements of {\bf E} did not converge to zero.
If INFO is not present and an error occurs, then the program is terminated with an error message.
References: [1] and [17,9,20].

Susan Blackford 2001-08-19