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RedHat 9 (Linux i386) - man page for dppcon (redhat section l)

DPPCON(l)					)					DPPCON(l)

NAME
       DPPCON - estimate the reciprocal of the condition number (in the 1-norm) of a real symmet-
       ric positive definite packed matrix using the Cholesky factorization A =  U**T*U  or  A	=
       L*L**T computed by DPPTRF

SYNOPSIS
       SUBROUTINE DPPCON( UPLO, N, AP, ANORM, RCOND, WORK, IWORK, INFO )

	   CHARACTER	  UPLO

	   INTEGER	  INFO, N

	   DOUBLE	  PRECISION ANORM, RCOND

	   INTEGER	  IWORK( * )

	   DOUBLE	  PRECISION AP( * ), WORK( * )

PURPOSE
       DPPCON  estimates the reciprocal of the condition number (in the 1-norm) of a real symmet-
       ric positive definite packed matrix using the Cholesky factorization A =  U**T*U  or  A	=
       L*L**T  computed  by DPPTRF.  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) DOUBLE PRECISION array, dimension (N*(N+1)/2)
	       The triangular factor U or L from the Cholesky factorization A =  U**T*U  or  A	=
	       L*L**T,	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) DOUBLE PRECISION
	       The 1-norm (or infinity-norm) of the symmetric matrix A.

       RCOND   (output) 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    (workspace) DOUBLE PRECISION array, dimension (3*N)

       IWORK   (workspace) INTEGER 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 				DPPCON(l)


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