zsycon (l)  Linux Man Pages
zsycon: estimates the reciprocal of the condition number (in the 1norm) of a complex symmetric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF
Command to display zsycon
manual in Linux: $ man l zsycon
NAME
ZSYCON  estimates the reciprocal of the condition number (in the 1norm) of a complex symmetric 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 symmetric 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.
= aqUaq: Upper triangular, form is A = U*D*U**T;
= aqLaq: 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
Pages related to zsycon
 zsycon (3)
 zsyequb (l)  computes row and column scalings intended to equilibrate a symmetric matrix A and reduce its condition number (with respect to the twonorm)
 zsymm (l)  performs one of the matrixmatrix operations C := alpha*A*B + beta*C,
 zsymv (l)  performs the matrixvector operation y := alpha*A*x + beta*y,
 zsyr (l)  performs the symmetric rank 1 operation A := alpha*x*( xaq ) + A,
 zsyr2k (l)  performs one of the symmetric rank 2k operations C := alpha*A*Baq + alpha*B*Aaq + beta*C,
 zsyrfs (l)  improves the computed solution to a system of linear equations when the coefficient matrix is symmetric indefinite, and provides error bounds and backward error estimates for the solution
 zsyrfsx (l)  ZSYRFSX improve the computed solution to a system of linear equations when the coefficient matrix is symmetric indefinite, and provides error bounds and backward error estimates for the solution