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LAPACK version 3.0
dppcon(3)

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

SYNTAX
  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( * )

DESCRIPTION
  DPPCON estimates the reciprocal of the condition number (in the 1-norm) of
  a real symmetric 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