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dptcon.f(3)				      LAPACK				      dptcon.f(3)

NAME
       dptcon.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dptcon (N, D, E, ANORM, RCOND, WORK, INFO)
	   DPTCON

Function/Subroutine Documentation
   subroutine dptcon (integerN, double precision, dimension( * )D, double precision, dimension( *
       )E, double precisionANORM, double precisionRCOND, double precision, dimension( * )WORK,
       integerINFO)
       DPTCON

       Purpose:

	    DPTCON computes the reciprocal of the condition number (in the
	    1-norm) of a real symmetric positive definite tridiagonal matrix
	    using the factorization A = L*D*L**T or A = U**T*D*U computed by
	    DPTTRF.

	    Norm(inv(A)) is computed by a direct method, and the reciprocal of
	    the condition number is computed as
			 RCOND = 1 / (ANORM * norm(inv(A))).

       Parameters:
	   N

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

	   D

		     D is DOUBLE PRECISION array, dimension (N)
		     The n diagonal elements of the diagonal matrix D from the
		     factorization of A, as computed by DPTTRF.

	   E

		     E is DOUBLE PRECISION array, dimension (N-1)
		     The (n-1) off-diagonal elements of the unit bidiagonal factor
		     U or L from the factorization of A,  as computed by DPTTRF.

	   ANORM

		     ANORM is DOUBLE PRECISION
		     The 1-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 the
		     1-norm of inv(A) computed in this routine.

	   WORK

		     WORK is DOUBLE PRECISION 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

       Further Details:

	     The method used is described in Nicholas J. Higham, "Efficient
	     Algorithms for Computing the Condition Number of a Tridiagonal
	     Matrix", SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.

       Definition at line 119 of file dptcon.f.

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

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