SGET01
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
Purpose
SGET01 reconstructs a matrix A from its L*U factorization and
computes the residual
norm(L*U - A) / ( N * norm(A) * EPS ),
where EPS is the machine epsilon.
computes the residual
norm(L*U - A) / ( N * norm(A) * EPS ),
where EPS is the machine epsilon.
Arguments
| M |
(input) INTEGER
The number of rows of the matrix A. M >= 0.
|
| N |
(input) INTEGER
The number of columns of the matrix A. N >= 0.
|
| A |
(input) REAL array, dimension (LDA,N)
The original M x N matrix A.
|
| LDA |
(input) INTEGER
The leading dimension of the array A. LDA >= max(1,M).
|
| AFAC |
(input/output) REAL array, dimension (LDAFAC,N)
The factored form of the matrix A. AFAC contains the factors
L and U from the L*U factorization as computed by SGETRF. Overwritten with the reconstructed matrix, and then with the difference L*U - A. |
| LDAFAC |
(input) INTEGER
The leading dimension of the array AFAC. LDAFAC >= max(1,M).
|
| IPIV |
(input) INTEGER array, dimension (N)
The pivot indices from SGETRF.
|
| RWORK |
(workspace) REAL array, dimension (M)
|
| RESID |
(output) REAL
norm(L*U - A) / ( N * norm(A) * EPS )
|