NAME

       dppcon.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dppcon (UPLO, N, AP, ANORM, RCOND, WORK, IWORK, INFO)
           DPPCON

Function/Subroutine Documentation

   subroutine dppcon (characterUPLO, integerN, double precision, dimension( * )AP, double
       precisionANORM, double precisionRCOND, double precision, dimension( * )WORK, integer,
       dimension( * )IWORK, integerINFO)
       DPPCON

       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))).

       Parameters:
           UPLO

                     UPLO is CHARACTER*1
                     = 'U':  Upper triangle of A is stored;
                     = 'L':  Lower triangle of A is stored.

           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           AP

                     AP is 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

                     ANORM is DOUBLE PRECISION
                     The 1-norm (or infinity-norm) of the symmetric matrix A.

           RCOND

                     RCOND is 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

                     WORK is DOUBLE PRECISION array, dimension (3*N)

           IWORK

                     IWORK is INTEGER array, dimension (N)

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           November 2011

       Definition at line 119 of file dppcon.f.

Author

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