DPOCON(3)      LAPACK routine of NEC Numeric Library Collection      DPOCON(3)



NAME
       DPOCON

SYNOPSIS
       SUBROUTINE DPOCON (UPLO, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO)



PURPOSE
            DPOCON estimates the reciprocal of the condition number (in the
            1-norm) of a real symmetric positive definite matrix using the
            Cholesky factorization A = U**T*U or A = L*L**T computed by DPOTRF.

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

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

           A         (input)
                     A is DOUBLE PRECISION array, dimension (LDA,N)
                     The triangular factor U or L from the Cholesky factorization
                     A = U**T*U or A = L*L**T, as computed by DPOTRF.

           LDA       (input)
                     LDA is INTEGER
                     The leading dimension of the array A.  LDA >= max(1,N).

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

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

           IWORK     (output)
                     IWORK is INTEGER array, dimension (N)

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



LAPACK routine                  31 October 2017                      DPOCON(3)