LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  checon (UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK, INFO) 
CHECON 
subroutine checon  (  character  UPLO, 
integer  N,  
complex, dimension( lda, * )  A,  
integer  LDA,  
integer, dimension( * )  IPIV,  
real  ANORM,  
real  RCOND,  
complex, dimension( * )  WORK,  
integer  INFO  
) 
CHECON
Download CHECON + dependencies [TGZ] [ZIP] [TXT]CHECON estimates the reciprocal of the condition number of a complex Hermitian matrix A using the factorization A = U*D*U**H or A = L*D*L**H computed by CHETRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
[in]  UPLO  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**H; = 'L': Lower triangular, form is A = L*D*L**H. 
[in]  N  N is INTEGER The order of the matrix A. N >= 0. 
[in]  A  A is COMPLEX array, dimension (LDA,N) The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by CHETRF. 
[in]  LDA  LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). 
[in]  IPIV  IPIV is INTEGER array, dimension (N) Details of the interchanges and the block structure of D as determined by CHETRF. 
[in]  ANORM  ANORM is REAL The 1norm of the original matrix A. 
[out]  RCOND  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 1norm of inv(A) computed in this routine. 
[out]  WORK  WORK is COMPLEX array, dimension (2*N) 
[out]  INFO  INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value 
Definition at line 125 of file checon.f.