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

SYNOPSIS
     SUBROUTINE DSPCON( UPLO, N, AP, IPIV,  ANORM,  RCOND,  WORK,
               IWORK, INFO )

     CHARACTER UPLO

     INTEGER INFO, N

     DOUBLE PRECISION ANORM, RCOND

     INTEGER IPIV( * ), IWORK( * )

     DOUBLE PRECISION AP( * ), WORK( * )



     #include <sunperf.h>

     void dspcon(char uplo, int n, double *dap, int *ipivot, dou-
               ble anorm, double *drcond, int *info);

PURPOSE
     DSPCON estimates the reciprocal of the condition number  (in
     the  1-norm)  of  a real symmetric packed matrix A using the
     factorization A = U*D*U**T  or  A  =  L*D*L**T  computed  by
     DSPTRF.

     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.

     AP        (input)   DOUBLE   PRECISION   array,    dimension
               (N*(N+1)/2)
               The block diagonal matrix D  and  the  multipliers
               used  to  obtain  the factor U or L as computed by
               DSPTRF, stored as a packed triangular matrix.

     IPIV      (input) INTEGER array, dimension (N)
               Details of the interchanges and the  block  struc-
               ture of D as determined by DSPTRF.

     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 ille-
               gal value

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