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



NAME
       CGECON

SYNOPSIS
       SUBROUTINE CGECON (NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK, INFO)



PURPOSE
            CGECON estimates the reciprocal of the condition number of a general
            complex matrix A, in either the 1-norm or the infinity-norm, using
            the LU factorization computed by CGETRF.

            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)) ).




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

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

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

           ANORM     (input)
                     ANORM is REAL
                     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     (output)
                     RCOND is REAL
                     The reciprocal of the condition number of the matrix A,
                     computed as RCOND = 1/(norm(A) * norm(inv(A))).

           WORK      (output)
                     WORK is COMPLEX array, dimension (2*N)

           RWORK     (output)
                     RWORK is REAL array, dimension (2*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                      CGECON(3)