cppcon(3F)

NAME
     CPPCON - estimate the reciprocal of the condition number (in the 1-norm)
     of a complex Hermitian positive definite packed matrix using the Cholesky
     factorization A = U**H*U or A = L*L**H computed by CPPTRF

SYNOPSIS
     SUBROUTINE CPPCON( UPLO, N, AP, ANORM, RCOND, WORK, RWORK, INFO )

         CHARACTER      UPLO

         INTEGER        INFO, N

         REAL           ANORM, RCOND

         REAL           RWORK( * )

         COMPLEX        AP( * ), WORK( * )

PURPOSE
     CPPCON estimates the reciprocal of the condition number (in the 1-norm)
     of a complex Hermitian positive definite packed matrix using the Cholesky
     factorization A = U**H*U or A = L*L**H computed by CPPTRF.

     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
             = 'U':  Upper triangle of A is stored;
             = 'L':  Lower triangle of A is stored.

     N       (input) INTEGER
             The order of the matrix A.  N >= 0.

     AP      (input) COMPLEX array, dimension (N*(N+1)/2)
             The triangular factor U or L from the Cholesky factorization A =
             U**H*U or A = L*L**H, packed columnwise in a linear array.  The
             j-th column of U or L is stored in the array AP as follows:  if
             UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j; if UPLO =
             'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.

     ANORM   (input) REAL
             The 1-norm (or infinity-norm) of the Hermitian 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
             1-norm of inv(A) computed in this routine.
     WORK    (workspace) COMPLEX array, dimension (2*N)

     RWORK   (workspace) REAL array, dimension (N)

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