DGECON man page on IRIX

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DGECON(3F)							    DGECON(3F)

NAME
     DGECON - estimate the reciprocal of the condition number of a general
     real matrix A, in either the 1-norm or the infinity-norm, using the LU
     factorization computed by DGETRF

SYNOPSIS
     SUBROUTINE DGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO )

	 CHARACTER	NORM

	 INTEGER	INFO, LDA, N

	 DOUBLE		PRECISION ANORM, RCOND

	 INTEGER	IWORK( * )

	 DOUBLE		PRECISION A( LDA, * ), WORK( * )

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

     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) DOUBLE PRECISION array, dimension (LDA,N)
	     The factors L and U from the factorization A = P*L*U as computed
	     by DGETRF.

     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))).

									Page 1

DGECON(3F)							    DGECON(3F)

     WORK    (workspace) DOUBLE PRECISION array, dimension (4*N)

     IWORK   (workspace) INTEGER array, dimension (N)

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

									Page 2

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