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**A**
*(input/output)* **REAL** or **COMPLEX** square
array, shape .

On entry, the matrix .

If = 'U',
the upper triangular part of **A** contains the upper
triangular part
of the matrix , and the strictly lower triangular part of
is not referenced.

If = 'L', the lower
triangular part of contains the lower triangular part of
the matrix , and the strictly upper triangular part of
is not referenced.

On exit, the block diagonal matrix and the multipliers used to
obtain the factor or from the factorization of .

- B
- (
*input/output*) **REAL** or **COMPLEX** array, shape
with
or shape with
.

On entry, the matrix .

On exit, the solution matrix .

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

Default value: 'U'.

- IPIV
*Optional (output)* **INTEGER** array, shape
with
.

Details of the row and column interchanges and
the block structure of .

If
, then rows and columns and
were interchanged, and is a
diagonal block.

If
, then there are two cases:

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

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

**References**: [1] and [17,9,20,21].

** Next:** Examples
** Up:** Symmetric Indefinite Linear Systems
** Previous:** Purpose
** Contents**
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Susan Blackford
2001-08-19