ZPOCON(l) ) ZPOCON(l)NAME
ZPOCON - estimate the reciprocal of the condition number (in the
1-norm) of a complex Hermitian positive definite matrix using the
Cholesky factorization A = U**H*U or A = L*L**H computed by ZPOTRF
SYNOPSIS
SUBROUTINE ZPOCON( UPLO, N, A, LDA, ANORM, RCOND, WORK, RWORK, INFO )
CHARACTER UPLO
INTEGER INFO, LDA, N
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION RWORK( * )
COMPLEX*16 A( LDA, * ), WORK( * )
PURPOSE
ZPOCON estimates the reciprocal of the condition number (in the 1-norm)
of a complex Hermitian positive definite matrix using the Cholesky fac‐
torization A = U**H*U or A = L*L**H computed by ZPOTRF. 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
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
N (input) INTEGER
The order of the matrix A. N >= 0.
A (input) COMPLEX*16 array, dimension (LDA,N)
The triangular factor U or L from the Cholesky factorization A
= U**H*U or A = L*L**H, as computed by ZPOTRF.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
ANORM (input) DOUBLE PRECISION
The 1-norm (or infinity-norm) of the Hermitian matrix A.
RCOND (output) DOUBLE PRECISION
The reciprocal of the condition number of the matrix A, com‐
puted as RCOND = 1/(ANORM * AINVNM), where AINVNM is an esti‐
mate of the 1-norm of inv(A) computed in this routine.
WORK (workspace) COMPLEX*16 array, dimension (2*N)
RWORK (workspace) DOUBLE PRECISION array, dimension (N)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
LAPACK version 3.0 15 June 2000 ZPOCON(l)
