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


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  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 num­
       ber 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),

               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 ille­
               gal value


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