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LAPACK version 3.0
dsycon(3)

PURPOSE
  DSYCON - estimate the reciprocal of the condition number (in the 1-norm) of
  a real symmetric matrix A using the factorization A = U*D*U**T or A =
  L*D*L**T computed by DSYTRF

SYNTAX
  SUBROUTINE DSYCON( UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK, IWORK, INFO )

      CHARACTER	     UPLO

      INTEGER	     INFO, LDA, N

      DOUBLE	     PRECISION ANORM, RCOND

      INTEGER	     IPIV( * ), IWORK( * )

      DOUBLE	     PRECISION A( LDA, * ), WORK( * )

DESCRIPTION
  DSYCON estimates the reciprocal of the condition number (in the 1-norm) of
  a real symmetric matrix A using the factorization A = U*D*U**T or A =
  L*D*L**T computed by DSYTRF.	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
	  Specifies whether the details of the factorization are stored as an
	  upper or lower triangular matrix.  = 'U':  Upper triangular, form
	  is A = U*D*U**T;
	  = 'L':  Lower triangular, form is A = L*D*L**T.

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

  A	  (input) DOUBLE PRECISION array, dimension (LDA,N)
	  The block diagonal matrix D and the multipliers used to obtain the
	  factor U or L as computed by DSYTRF.

  LDA	  (input) INTEGER
	  The leading dimension of the array A.	 LDA >= max(1,N).

  IPIV	  (input) INTEGER array, dimension (N)
	  Details of the interchanges and the block structure of D as
	  determined by DSYTRF.

  ANORM	  (input) DOUBLE PRECISION
	  The 1-norm of the original 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 (2*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