checon.f (3) Linux Manual Page

checon.f –

Synopsis

Functions/Subroutines

subroutine checon (UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK, INFO)
CHECON

Function/Subroutine Documentation

subroutine checon (characterUPLO, integerN, complex, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, realANORM, realRCOND, complex, dimension( * )WORK, integerINFO)

CHECON

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))).

 

Parameters:

UPLO

 UPLO is 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

 N is INTEGER

 The order of the matrix A. N >= 0.

A

 A is 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

 LDA is INTEGER

 The leading dimension of the array A. LDA >= max(1,N).

IPIV

 IPIV is INTEGER array, dimension (N)

 Details of the interchanges and the block structure of D

 as determined by CHETRF.

ANORM

 ANORM is REAL

 The 1-norm of the original matrix A.

RCOND

 RCOND is REAL

 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

 WORK is COMPLEX array, dimension (2*N)

INFO

 INFO is INTEGER

 = 0: successful exit

 < 0: if INFO = -i, the i-th argument had an illegal value

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 125 of file checon.f.

Author

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