redhat man page for cppcon

CPPCON(l)								 )								 CPPCON(l)

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

LAPACK version 3.0						   15 June 2000 							 CPPCON(l)