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dgtcon.f(3)				      LAPACK				      dgtcon.f(3)

NAME
       dgtcon.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dgtcon (NORM, N, DL, D, DU, DU2, IPIV, ANORM, RCOND, WORK, IWORK, INFO)
	   DGTCON

Function/Subroutine Documentation
   subroutine dgtcon (characterNORM, integerN, double precision, dimension( * )DL, double
       precision, dimension( * )D, double precision, dimension( * )DU, double precision,
       dimension( * )DU2, integer, dimension( * )IPIV, double precisionANORM, double
       precisionRCOND, double precision, dimension( * )WORK, integer, dimension( * )IWORK,
       integerINFO)
       DGTCON

       Purpose:

	    DGTCON estimates the reciprocal of the condition number of a real
	    tridiagonal matrix A using the LU factorization as computed by
	    DGTTRF.

	    An estimate is obtained for norm(inv(A)), and the reciprocal of the
	    condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).

       Parameters:
	   NORM

		     NORM is 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

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

	   DL

		     DL is DOUBLE PRECISION array, dimension (N-1)
		     The (n-1) multipliers that define the matrix L from the
		     LU factorization of A as computed by DGTTRF.

	   D

		     D is DOUBLE PRECISION array, dimension (N)
		     The n diagonal elements of the upper triangular matrix U from
		     the LU factorization of A.

	   DU

		     DU is DOUBLE PRECISION array, dimension (N-1)
		     The (n-1) elements of the first superdiagonal of U.

	   DU2

		     DU2 is DOUBLE PRECISION array, dimension (N-2)
		     The (n-2) elements of the second superdiagonal of U.

	   IPIV

		     IPIV is INTEGER array, dimension (N)
		     The pivot indices; for 1 <= i <= n, row i of the matrix was
		     interchanged with row IPIV(i).  IPIV(i) will always be either
		     i or i+1; IPIV(i) = i indicates a row interchange was not
		     required.

	   ANORM

		     ANORM is 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

		     RCOND is DOUBLE PRECISION
		     The reciprocal of the condition number of the matrix A,
		     computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
		     estimate of the 1-norm of inv(A) computed in this routine.

	   WORK

		     WORK is DOUBLE PRECISION array, dimension (2*N)

	   IWORK

		     IWORK is INTEGER array, dimension (N)

	   INFO

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

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Definition at line 146 of file dgtcon.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      dgtcon.f(3)
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