CTRT01
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
Purpose
CTRT01 computes the residual for a triangular matrix A times its
inverse:
RESID = norm( A*AINV - I ) / ( N * norm(A) * norm(AINV) * EPS ),
where EPS is the machine epsilon.
inverse:
RESID = norm( A*AINV - I ) / ( N * norm(A) * norm(AINV) * EPS ),
where EPS is the machine epsilon.
Arguments
| UPLO |
(input) CHARACTER*1
Specifies whether the matrix A is upper or lower triangular.
= 'U': Upper triangular = 'L': Lower triangular |
| DIAG |
(input) CHARACTER*1
Specifies whether or not the matrix A is unit triangular.
= 'N': Non-unit triangular = 'U': Unit triangular |
| N |
(input) INTEGER
The order of the matrix A. N >= 0.
|
| A |
(input) COMPLEX array, dimension (LDA,N)
The triangular matrix A. If UPLO = 'U', the leading n by n
upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading n by n lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced. If DIAG = 'U', the diagonal elements of A are also not referenced and are assumed to be 1. |
| LDA |
(input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
|
| AINV |
(input) COMPLEX array, dimension (LDAINV,N)
On entry, the (triangular) inverse of the matrix A, in the
same storage format as A. On exit, the contents of AINV are destroyed. |
| LDAINV |
(input) INTEGER
The leading dimension of the array AINV. LDAINV >= max(1,N).
|
| RCOND |
(output) REAL
The reciprocal condition number of A, computed as
1/(norm(A) * norm(AINV)). |
| RWORK |
(workspace) REAL array, dimension (N)
|
| RESID |
(output) REAL
norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS )
|