CXML
        	    
LAPACK version 3.0
dlaed6(3)

PURPOSE
  DLAED6 - compute the positive or negative root (closest to the origin) of
  z(1) z(2) z(3) f(x) = rho + --------- + ---------- + --------- d(1)-x
  d(2)-x d(3)-x	 It is assumed that  if ORGATI = .true

SYNTAX
  SUBROUTINE DLAED6( KNITER, ORGATI, RHO, D, Z, FINIT, TAU, INFO )

      LOGICAL	     ORGATI

      INTEGER	     INFO, KNITER

      DOUBLE	     PRECISION FINIT, RHO, TAU

      DOUBLE	     PRECISION D( 3 ), Z( 3 )

DESCRIPTION
  DLAED6 computes the positive or negative root (closest to the origin) of
  z(1) z(2) z(3) f(x) = rho + --------- + ---------- + --------- d(1)-x
  d(2)-x d(3)-x It is assumed that if ORGATI = .true. the root is between
  d(2) and d(3);       otherwise it is between d(1) and d(2)

  This routine will be called by DLAED4 when necessary. In most cases, the
  root sought is the smallest in magnitude, though it might not be in some
  extremely rare situations.

ARGUMENTS
  KNITER       (input) INTEGER
	       Refer to DLAED4 for its significance.

  ORGATI       (input) LOGICAL
	       If ORGATI is true, the needed root is between d(2) and d(3);
	       otherwise it is between d(1) and d(2).  See DLAED4 for further
	       details.

  RHO	       (input) DOUBLE PRECISION
	       Refer to the equation f(x) above.

  D	       (input) DOUBLE PRECISION array, dimension (3)
	       D satisfies d(1) < d(2) < d(3).

  Z	       (input) DOUBLE PRECISION array, dimension (3)
	       Each of the elements in z must be positive.

  FINIT	       (input) DOUBLE PRECISION
	       The value of f at 0. It is more accurate than the one
	       evaluated inside this routine (if someone wants to do so).

  TAU	       (output) DOUBLE PRECISION
	       The root of the equation f(x).

  INFO	       (output) INTEGER
	       = 0: successful exit
	       > 0: if INFO = 1, failure to converge

FURTHER DETAILS
  Based on contributions by
     Ren-Cang Li, Computer Science Division, University of California
     at Berkeley, USA