NAME

SRC/zhecon_rook.f

SYNOPSIS

Functions/Subroutines

subroutine zhecon_rook (uplo, n, a, lda, ipiv, anorm, rcond, work, info)
ZHECON_ROOK estimates the reciprocal of the condition number fort HE matrices using factorization obtained with one of the bounded diagonal pivoting methods (max 2 interchanges)

Function/Subroutine Documentation

subroutine zhecon_rook (character uplo, integer n, complex16, dimension( lda, ) a, integer lda, integer, dimension( * ) ipiv, double precision anorm, double precision rcond, complex16, dimension( ) work, integer info)

ZHECON_ROOK estimates the reciprocal of the condition number fort HE matrices using factorization obtained with one of the bounded diagonal pivoting methods (max 2 interchanges)

Purpose:



 ZHECON_ROOK 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_ROOK.


 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 is INTEGER


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



          A is 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 CHETRF_ROOK.

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_ROOK.

ANORM



          ANORM is DOUBLE PRECISION


          The 1-norm of the original matrix A.

RCOND



          RCOND is 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 1-norm of inv(A) computed in this routine.

WORK



          WORK is COMPLEX*16 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.

Contributors:



  June 2017,  Igor Kozachenko,


                  Computer Science Division,


                  University of California, Berkeley


  September 2007, Sven Hammarling, Nicholas J. Higham, Craig Lucas,


                  School of Mathematics,


                  University of Manchester

Definition at line 137 of file zhecon_rook.f.

Author