redhat man page for zgecon

ZGECON(l)								 )								 ZGECON(l)

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

LAPACK version 3.0						   15 June 2000 							 ZGECON(l)