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template<typename T>
void spcon(char *uplo, integer *n, T *ap, integer *ipiv, T *anorm, T *rcond, T *work, integer *iwork, integer *info)# SPCON estimates the reciprocal of the condition number.
Purpose:
SPCON estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric packed matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by SSPTRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
- Parameters:
UPLO – [in]
UPLO is CHARACTER*1
Specifies whether the details of the factorization are stored as an upper or lower triangular matrix.
= ‘U’: Upper triangular, form is A = U*D*U**T;
= ‘L’: Lower triangular, form is A = L*D*L**T.
N – [in]
N is INTEGER
The order of the matrix A. N >= 0.
AP – [in]
AP is REAL array, dimension (N*(N+1)/2)
The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSPTRF, stored as a packed triangular matrix.
IPIV – [in]
IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as determined by SSPTRF.
ANORM – [in]
ANORM is REAL
The 1-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/(ANORM * AINVNM), where AINVNM is an estimate of the 1-norm of inv(A) computed in this routine.
WORK – [out] WORK is REAL array, dimension (2*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