checon (l)  Linux Manuals
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
Command to display checon
manual in Linux: $ man l checon
NAME
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
SYNOPSIS
 SUBROUTINE CHECON(

UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK,
INFO )

CHARACTER
UPLO

INTEGER
INFO, LDA, N

REAL
ANORM, RCOND

INTEGER
IPIV( * )

COMPLEX
A( LDA, * ), WORK( * )
PURPOSE
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))).
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**H;
= aqLaq: Lower triangular, form is A = L*D*L**H.
 N (input) INTEGER

The order of the matrix A. N >= 0.
 A (input) 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.
 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 CHETRF.
 ANORM (input) REAL

The 1norm of the original matrix A.
 RCOND (output) 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.
 WORK (workspace) COMPLEX array, dimension (2*N)

 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
Pages related to checon
 checon (3)
 cheequb (l)  computes row and column scalings intended to equilibrate a symmetric matrix A and reduce its condition number (with respect to the twonorm)
 cheev (l)  computes all eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A
 cheevd (l)  computes all eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A
 cheevr (l)  computes selected eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A
 cheevx (l)  computes selected eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A
 chegs2 (l)  reduces a complex Hermitiandefinite generalized eigenproblem to standard form
 chegst (l)  reduces a complex Hermitiandefinite generalized eigenproblem to standard form