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template<typename T>
void gecon(char *norm, integer *n, T *a, integer *lda, T *anorm, T *rcond, T *work, integer *iwork, integer *info)# GECON estimates the reciprocal of the condition number of a general real matrix A.
Purpose:
GECON estimates the reciprocal of the condition number of a general real matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by SGETRF. An estimate is obtained for norm(inv(A)), and 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.
N – [in]
N is INTEGER
The order of the matrix A. N >= 0.
A – [in]
A is REAL array, dimension (LDA,N)
The factors L and U from the factorization A = P*L*U as computed by SGETRF.
LDA – [in]
LDA is INTEGER
The leading dimension of the array A. LDA >= fla_max(1,N).
ANORM – [in]
ANORM is REAL
If NORM = ‘1’ or ‘O’, the 1-norm of the original matrix A.
If NORM = ‘I’, the infinity-norm of the original matrix A.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 (4*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