SRC/dgecon.f(3)            Library Functions Manual            SRC/dgecon.f(3)

NAME
       SRC/dgecon.f

SYNOPSIS
   Functions/Subroutines
       subroutine dgecon (norm, n, a, lda, anorm, rcond, work, iwork, info)
           DGECON

Function/Subroutine Documentation
   subroutine dgecon (character norm, integer n, double precision, dimension(
       lda, * ) a, integer lda, double precision anorm, double precision
       rcond, double precision, dimension( * ) work, integer, dimension( * )
       iwork, integer info)
       DGECON

       Purpose:


            DGECON estimates the reciprocal of the condition number of a general
            real matrix A, in either the 1-norm or the infinity-norm, using
            the LU factorization computed by DGETRF.

            An estimate is obtained for norm(inv(A)), and the reciprocal of the
            condition number is computed as
               RCOND = 1 / ( norm(A) * norm(inv(A)) ).

       Parameters
           NORM

                     NORM is CHARACTER*1
                     Specifies whether the 1-norm condition number or the
                     infinity-norm condition number is required:
                     = '1' or 'O':  1-norm;
                     = 'I':         Infinity-norm.

           N

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

           A

                     A is DOUBLE PRECISION array, dimension (LDA,N)
                     The factors L and U from the factorization A = P*L*U
                     as computed by DGETRF.

           LDA

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

           ANORM

                     ANORM is DOUBLE PRECISION
                     If NORM = '1' or 'O', the 1-norm of the original matrix A.
                     If NORM = 'I', the infinity-norm of the original matrix A.

           RCOND

                     RCOND is DOUBLE PRECISION
                     The reciprocal of the condition number of the matrix A,
                     computed as RCOND = 1/(norm(A) * norm(inv(A))).

           WORK

                     WORK is DOUBLE PRECISION array, dimension (4*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.
                           NaNs are illegal values for ANORM, and they propagate to
                           the output parameter RCOND.
                           Infinity is illegal for ANORM, and it propagates to the output
                           parameter RCOND as 0.
                     = 1:  if RCOND = NaN, or
                              RCOND = Inf, or
                              the computed norm of the inverse of A is 0.
                           In the latter, RCOND = 0 is returned.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 130 of file dgecon.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                 SRC/dgecon.f(3)