DLA_SYRPVGRW
Purpose
DLA_SYRPVGRW computes the reciprocal pivot growth factor
norm(A)/norm(U). The "max absolute element" norm is used. If this is
much less than 1, the stability of the LU factorization of the
(equilibrated) matrix A could be poor. This also means that the
solution X, estimated condition numbers, and error bounds could be
unreliable.
norm(A)/norm(U). The "max absolute element" norm is used. If this is
much less than 1, the stability of the LU factorization of the
(equilibrated) matrix A could be poor. This also means that the
solution X, estimated condition numbers, and error bounds could be
unreliable.
Arguments
| UPLO |
(input) CHARACTER*1
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored. |
| N |
(input) INTEGER
The number of linear equations, i.e., the order of the
matrix A. N >= 0. |
| INFO |
(input) INTEGER
The value of INFO returned from DSYTRF, .i.e., the pivot in
column INFO is exactly 0. |
| NCOLS |
(input) INTEGER
The number of columns of the matrix A. NCOLS >= 0.
|
| A |
(input) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the N-by-N matrix A.
|
| LDA |
(input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
|
| AF |
(input) DOUBLE PRECISION array, dimension (LDAF,N)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by DSYTRF. |
| LDAF |
(input) INTEGER
The leading dimension of the array AF. LDAF >= max(1,N).
|
| IPIV |
(input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by DSYTRF. |
| WORK |
(input) DOUBLE PRECISION array, dimension (2*N)
|