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NAME
     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( * )



     #include <sunperf.h>

     void dppcon(char uplo, int n,  double  *dap,  double  anorm,
               double *drcond, int *info);

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 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 ille-
               gal value

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