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


SYNOPSIS

       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( * )


PURPOSE

       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 struc­
               ture of D as determined by DSYTRF.

       ANORM   (input) DOUBLE PRECISION
               The 1-norm of the original matrix A.

               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 ille­
               gal value


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