zgecon(3F)

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