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dlaed6 examples
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Man Page Details
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 Purpose
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  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
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  Based on contributions by
     Ren-Cang Li, Computer Science Division, University of California
     at Berkeley, USA

