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- D
- (
*input*) **REAL** array, shape with
, where is the order of .

The diagonal of .

- E
- (
*input*) **REAL** or **COMPLEX** array,
shape with
.

The subdiagonal of .

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

The matrix .

- X
- (
*output*) **REAL** or **COMPLEX** array, shape
with
and
,
or shape with
.

The solution matrix .

- DF
*Optional* (*input or output*) **REAL**
array, shape with the same size as **D**.

If **FACT** = 'F', then **DF** is an input argument that
contains the diagonal of from the factorization of .

If 'N', then **DF** is an output argument that
contains the diagonal of from the factorization of .

- EF
*Optional* (*input or output*) **REAL**
or **COMPLEX** array, shape with the same size as **E**.

If **FACT** = 'F', then **EF** is an input argument that
contains the subdiagonal of from the factorization of .

If **FACT** = 'N', then **EF** is an output argument that
contains the subdiagonal of from the factorization of .

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

Specifies whether the factored form of has been supplied on entry.

Default value: 'N'.

- FERR
*Optional* (*output*) **REAL** array
of shape , with
, or **REAL** scalar.

The estimated forward error bound for each solution vector
(the column of the solution matrix ).
If is the true solution corresponding to ,
is an estimated upper bound for the magnitude of the largest
element in () divided by the magnitude of the
largest element in .

- BERR
*Optional* (*output*) **REAL** array
of shape , with
, or **REAL** scalar.

The componentwise relative backward error of each solution
vector (i.e., the smallest relative change in any
element of or that makes an exact solution).

- RCOND
*Optional* (*output)* **REAL**.

The estimate of the reciprocal condition number of the matrix
. If is less than the
machine precision, the matrix
is singular to working precision. This condition is
indicated by a return code of
.

- 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].

**Subsections**

** Next:** Example (from Program LA_PTSVX_EXAMPLE)
** Up:** Symmetric/Hermitian Positive Definite Linear
** Previous:** Description
** Contents**
** Index**
Susan Blackford
2001-08-19