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template<typename T>
void trcon(char *norm, char *uplo, char *diag, integer *n, T *a, integer *lda, T *rcond, T *work, integer *iwork, integer *info)# TRCON estimates the reciprocal of the condition number of a triangular matrix A.
Purpose:
TRCON estimates the reciprocal of the condition number of a triangular matrix A, in either the 1-norm or the infinity-norm. The norm of A is computed and an estimate is obtained for norm(inv(A)), then the reciprocal of the condition number is computed as RCOND = 1 / ( norm(A) * norm(inv(A))).
- Parameters:
NORM – [in]
NORM is CHARACTER*1
Specifies whether the 1-norm condition number or the infinity-norm condition number is required:
= ‘1’ or ‘O’: 1-norm;
= ‘I’: Infinity-norm.
UPLO – [in]
UPLO is CHARACTER*1
= ‘U’: A is upper triangular;
= ‘L’: A is lower triangular.DIAG – [in]
DIAG is CHARACTER*1
= ‘N’: A is non-unit triangular;
= ‘U’: A is unit triangular.N – [in]
N is INTEGER
The order of the matrix A. N >= 0.
A – [in]
A is REAL 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 – [in]
LDA is INTEGER
The leading dimension of the array A. LDA >= fla_max(1,N).
RCOND – [out]
RCOND is REAL
The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORK – [out] WORK is REAL array, dimension (3*N)
IWORK – [out] IWORK is INTEGER array, dimension (N)
INFO – [out]
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value