SLAED6 (3lapack)

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



SYNOPSIS

  SUBROUTINE SLAED6( KNITER, ORGATI, RHO, D, Z, FINIT, TAU, INFO )

      LOGICAL        ORGATI

      INTEGER        INFO, KNITER

      REAL           FINIT, RHO, TAU

      REAL           D( 3 ), Z( 3 )

PURPOSE

  SLAED6 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
        otherwise it is between d(1) and d(2)

  This routine will be called by SLAED4 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 SLAED4 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 SLAED4 for further
               details.

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

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

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

  FINIT        (input) REAL
               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) REAL
               The root of the equation f(x).

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



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