
ZSYCON(l) ) ZSYCON(l)
NAME
ZSYCON  estimate the reciprocal of the condition number (in the 1norm) of a complex sym
metric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF
SYNOPSIS
SUBROUTINE ZSYCON( UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK, INFO )
CHARACTER UPLO
INTEGER INFO, LDA, N
DOUBLE PRECISION ANORM, RCOND
INTEGER IPIV( * )
COMPLEX*16 A( LDA, * ), WORK( * )
PURPOSE
ZSYCON estimates the reciprocal of the condition number (in the 1norm) of a complex sym
metric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF.
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**T;
= 'L': Lower triangular, form is A = L*D*L**T.
N (input) INTEGER
The order of the matrix A. N >= 0.
A (input) COMPLEX*16 array, dimension (LDA,N)
The block diagonal matrix D and the multipliers used to obtain the factor U or L
as computed by ZSYTRF.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
IPIV (input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as determined by ZSYTRF.
ANORM (input) DOUBLE PRECISION
The 1norm 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 1norm 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 ith argument had an illegal value
LAPACK version 3.0 15 June 2000 ZSYCON(l) 
