next up previous contents index
Next: Examples Up: Standard Nonsymmetric Eigenvalue Problems Previous: Purpose   Contents   Index

Arguments

A
(input/output) REAL or COMPLEX square array, shape $(:,:)$.
On entry, the matrix $A$.
On exit, the Schur form $T$.

w
(output) REAL or COMPLEX array, shape $(:)$ with $size({\it w}) = size({\bf A},1)$.
The computed eigenvalues in the order in which they appear on the diagonal of the Schur form $T$.
${\it w(:)}$ ::= WR(:), WI(:) $\mid$ W(:),
where
WR(:), WI(:) are of REAL type (for the real and imaginary parts) and W(:) is of COMPLEX type.
Note: If $A$ is real, then a complex-conjugate pair appear consecutively, with the eigenvalue having the positive imaginary part appearing first.

VS
Optional (output) REAL or COMPLEX square array, shape $(:,:)$ with $size$(VS,1) $= size$(A,1).
The matrix $Z$ of Schur vectors.

SELECT
Optional (input) LOGICAL FUNCTION.
LOGICAL FUNCTION SELECT( w$_j$ )
type(wp), INTENT(IN) :: w$_j$
where
type ::= REAL $\mid$ COMPLEX
wp ::= KIND(1.0) $\mid$ KIND(1.0D0)
w$_j$ ::= WR$_j$, WI$_j$ $\mid$ W$_j$




\begin{numbersec}
\item ${\bf SELECT}$\ must be declared as {\bf EXTERNAL} or a...
...FO}$\ is set
to $size({\bf A},1)+2$\ (see ${\bf INFO}$\ below).
\end{numbersec}
Note: Select must be present if SDIM is desired.

SDIM
Optional (output) INTEGER.
The number of eigenvalues (after sorting) for which SELECT $=$ .TRUE. (If $A$ is real, complex conjugate pairs for which SELECT $=$ .TRUE. for either eigenvalue count as 2).

INFO
Optional (output) INTEGER.

\begin{infoarg}
\item[{$=$\ 0:}] successful exit.
\item[{$<$\ 0:}] if {\bf INF...
...nderflow due to scaling.
\end{infoarg} $n$\ is the order of $A$.
\end{infoarg}
If ${\bf INFO}$ is not present and an error occurs, then the program is terminated with an error message.

References: [1] and [17,9,20].
next up previous contents index
Next: Examples Up: Standard Nonsymmetric Eigenvalue Problems Previous: Purpose   Contents   Index
Susan Blackford 2001-08-19