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RedHat 9 (Linux i386) - man page for ztrcon (redhat section l)

ZTRCON(l)					)					ZTRCON(l)

NAME
       ZTRCON  -  estimate  the  reciprocal  of the condition number of a triangular matrix A, in
       either the 1-norm or the infinity-norm

SYNOPSIS
       SUBROUTINE ZTRCON( NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, RWORK, INFO )

	   CHARACTER	  DIAG, NORM, UPLO

	   INTEGER	  INFO, LDA, N

	   DOUBLE	  PRECISION RCOND

	   DOUBLE	  PRECISION RWORK( * )

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

PURPOSE
       ZTRCON estimates the reciprocal of the condition number	of  a  triangular  matrix  A,  in
       either  the  1-norm  or	the  infinity-norm.  The norm of A is computed and an estimate is
       obtained for norm(inv(A)), then 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  num-
	       ber is required:
	       = '1' or 'O':  1-norm;
	       = 'I':	      Infinity-norm.

       UPLO    (input) CHARACTER*1
	       = 'U':  A is upper triangular;
	       = 'L':  A is lower triangular.

       DIAG    (input) CHARACTER*1
	       = 'N':  A is non-unit triangular;
	       = 'U':  A is unit triangular.

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

       A       (input) COMPLEX*16 array, dimension (LDA,N)
	       The  triangular matrix A.  If UPLO = 'U', the leading N-by-N upper triangular part
	       of the array A contains the upper triangular matrix, and the strictly lower trian-
	       gular part of A is not referenced.  If UPLO = 'L', the leading N-by-N lower trian-
	       gular part of the array A contains the lower triangular matrix, and  the  strictly
	       upper  triangular  part	of A is not referenced.  If DIAG = 'U', the diagonal ele-
	       ments of A are also not referenced and are assumed to be 1.

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

       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 (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 				ZTRCON(l)


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