NAME
ZHPCON - estimates the reciprocal of the condition number of a complex Hermitian packed matrix A using the factorization A = U*D*U**H or A = L*D*L**H computed by ZHPTRF
SYNOPSIS
- SUBROUTINE ZHPCON(
-
UPLO, N, AP, IPIV, ANORM, RCOND, WORK, INFO )
- CHARACTER
-
UPLO
- INTEGER
-
INFO, N
- DOUBLE
-
PRECISION ANORM, RCOND
- INTEGER
-
IPIV( * )
- COMPLEX*16
-
AP( * ), WORK( * )
PURPOSE
ZHPCON estimates the reciprocal of the condition number of a complex Hermitian packed matrix A using the factorization A = U*D*U**H or A = L*D*L**H computed by ZHPTRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
ARGUMENTS
- UPLO (input) 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.
- N (input) INTEGER
-
The order of the matrix A. N >= 0.
- AP (input) COMPLEX*16 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 ZHPTRF, stored as a packed triangular matrix.
- IPIV (input) INTEGER array, dimension (N)
-
Details of the interchanges and the block structure of D as determined by ZHPTRF.
- ANORM (input) DOUBLE PRECISION
-
The 1-norm of the original matrix A.
- RCOND (output) DOUBLE PRECISION
-
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 (workspace) COMPLEX*16 array, dimension (2*N)
- INFO (output) INTEGER
-
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value