ZPPCON(3)      LAPACK routine of NEC Numeric Library Collection      ZPPCON(3)



NAME
       ZPPCON

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



PURPOSE
            ZPPCON 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
            ZPPTRF.

            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)
                     UPLO is CHARACTER*1
                     = 'U':  Upper triangle of A is stored;
                     = 'L':  Lower triangle of A is stored.

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

           AP        (input)
                     AP is COMPLEX*16 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)
                     ANORM is DOUBLE PRECISION
                     The 1-norm (or infinity-norm) of the Hermitian matrix A.

           RCOND     (output)
                     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      (output)
                     WORK is COMPLEX*16 array, dimension (2*N)

           RWORK     (output)
                     RWORK is DOUBLE PRECISION array, dimension (N)

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



LAPACK routine                  31 October 2017                      ZPPCON(3)