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

## Arguments

AP
(input) REAL or COMPLEX array, shape with , where is the order of .
On entry, the upper or lower triangle of matrix in packed storage. The elements are stored columnwise as follows: 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'.

AFP
Optional (input or output) REAL or COMPLEX array, shape with the same size as AP.
If FACT = 'F', then AFP 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_SPSVX or LA_HPSVX and stored as a packed triangular matrix in the same storage format as .
If FACT = 'N', then AFP is an output argument that contains the block diagonal matrix and the multipliers used to obtain the factor or from the factorization of , stored as a packed triangular matrix in the same storage format as .

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 and on exit contains details of the interchanges and the block structure of (as described above).

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 . 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_SPSVX_EXAMPLE) Up: Symmetric Indefinite Linear Systems Previous: Description   Contents   Index
Susan Blackford 2001-08-19