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LAPACK version 3.0
dlasq3(3)

PURPOSE
  DLASQ3 - check for deflation, computes a shift (TAU) and calls dqds

SYNTAX
  SUBROUTINE DLASQ3( I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL, ITER,
		     NDIV, IEEE )

      LOGICAL	     IEEE

      INTEGER	     I0, ITER, N0, NDIV, NFAIL, PP

      DOUBLE	     PRECISION DESIG, DMIN, QMAX, SIGMA

      DOUBLE	     PRECISION Z( * )

DESCRIPTION
  DLASQ3 checks for deflation, computes a shift (TAU) and calls dqds. In case
  of failure it changes shifts, and tries again until output is positive.

ARGUMENTS
  I0	 (input) INTEGER
	 First index.

  N0	 (input) INTEGER
	 Last index.

  Z	 (input) DOUBLE PRECISION array, dimension ( 4*N )
	 Z holds the qd array.

  PP	 (input) INTEGER
	 PP=0 for ping, PP=1 for pong.

  DMIN	 (output) DOUBLE PRECISION
	 Minimum value of d.

  SIGMA	 (output) DOUBLE PRECISION
	 Sum of shifts used in current segment.

  DESIG	 (input/output) DOUBLE PRECISION
	 Lower order part of SIGMA

  QMAX	 (input) DOUBLE PRECISION
	 Maximum value of q.

  NFAIL	 (output) INTEGER
	 Number of times shift was too big.

  ITER	 (output) INTEGER
	 Number of iterations.

  NDIV	 (output) INTEGER
	 Number of divisions.

  TTYPE	 (output) INTEGER
	 Shift type.

  IEEE	 (input) LOGICAL
	 Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).