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zgecon

 NAME
      ZGECON - estimate 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 ZGETRF

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

          CHARACTER      NORM

          INTEGER        INFO, LDA, N

          DOUBLE         PRECISION ANORM, RCOND

          DOUBLE         PRECISION RWORK( * )

          COMPLEX*16     A( LDA, * ), WORK( * )

 PURPOSE
      ZGECON 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
      ZGETRF.

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

      A       (input) COMPLEX*16 array, dimension (LDA,N)
              The factors L and U from the factorization A = P*L*U
              as computed by ZGETRF.

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

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

      WORK    (workspace) COMPLEX*16 array, dimension (2*N)

      RWORK   (workspace) DOUBLE PRECISION array, dimension (2*N)

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