CHECON  -  estimate 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.
               = 'U':  Upper triangular, form is A = U*D*U**H;
               = 'L':  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  struc­
               ture of D as determined by CHETRF.

       ANORM   (input) REAL
               The 1-norm of the original matrix A.

               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    (workspace) COMPLEX array, dimension (2*N)

       INFO    (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille­
               gal value


Man(1) output converted with man2html