     Next: Example (from Program LA_SYSVX_EXAMPLE) Up: Symmetric Indefinite Linear Systems Previous: Description   Contents   Index

## Arguments

A
(input) REAL or COMPLEX square array, shape .
The symmetric or Hermitian matrix .
If UPLO = 'U', the upper triangular part of A contains the upper triangular part of the matrix , and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the lower triangular part of A contains the lower triangular part of the matrix , and the strictly upper triangular part of A is not referenced.

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 .

UPLO
Optional (input) CHARACTER(LEN=1). Default value: 'U'.

AF
Optional (input or output) REAL or COMPLEX array, shape with the same size as .
If FACT = 'F', then AF is an input argument that contains the block diagonal matrix and the multipliers used to obtain the factor or from the factorization of , returned by a previous call to LA_SYSVX or LA_HESVX.
If FACT = 'N', then AF is an output argument that contains the block diagonal matrix and the multipliers used to obtain the factor or from the factorization of .

IPIV
Optional (input or output) INTEGER array, shape with .
If FACT = 'F', then is an input argument that contains details of the row and column interchanges and the block structure of . If FACT = 'N', then IPIV is an output argument that contains details of the row and column interchanges and the block structure of ; as described above.

FACT
Optional (input) CHARACTER(LEN=1).
Specifies whether the factored form of the matrix 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 . The estimate is as reliable as the estimate for , and is almost always a slight overestimate of the true error.

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

INFO
(output) INTEGER If is not present and an error occurs, then the program is terminated with an error message.
References:  and [17,9,20,21].     Next: Example (from Program LA_SYSVX_EXAMPLE) Up: Symmetric Indefinite Linear Systems Previous: Description   Contents   Index
Susan Blackford 2001-08-19