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Arguments

AP
(input/output) REAL or COMPLEX array, shape $(:)$ with $size({\bf AP}) = n(n+1)/2$, where $n$ is the order of $A$.
On entry, the upper or lower triangle of matrix $A$ in packed storage. The elements are stored columnwise as follows:

\begin{displaymath}
\begin{array}{c\vert c\vert c}
A_{i,j} & i,j & {\bf UPLO} ...
... \leq i \leq n \end{array} & \mbox{ 'L'} \\ \hline
\end{array}\end{displaymath}

On exit, the factor $U$ or $L$ from the Cholesky factorization $A = U^HU$ or $A = LL^H$, in the same storage format as $A$.

B
(input/output) REAL or COMPLEX array, shape $(:,:)$ with $size({\bf B},1) = n$ or shape $(:)$ with $size({\bf B}) = n$.
On entry, the matrix $B$.
On exit, the solution matrix $X$.

UPLO
Optional (input) CHARACTER(LEN=1)

\begin{optionarg}
\item[{= 'U':}] Upper triangle of $A$\ is stored;
\item[{= 'L':}] Lower triangle of $A$\ is stored.
\end{optionarg}
Default value: 'U'.

INFO
Optional (output) INTEGER.

\begin{infoarg}
\item[{$=$\ 0:}] successful exit.
\item[{$<$\ 0:}] if ${\bf IN...
...n could not be
completed and the solution could not be computed.
\end{infoarg}
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