CXML
        	    
LAPACK version 3.0
slasq3(3)

PURPOSE
  SLASQ3 - check for deflation, computes a shift (TAU) and calls dqds

SYNTAX
  SUBROUTINE SLASQ3( I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL, ITER,
		     NDIV, IEEE )

      LOGICAL	     IEEE

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

      REAL	     DESIG, DMIN, QMAX, SIGMA

      REAL	     Z( * )

DESCRIPTION
  SLASQ3 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) REAL array, dimension ( 4*N )
	 Z holds the qd array.

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

  DMIN	 (output) REAL
	 Minimum value of d.

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

  DESIG	 (input/output) REAL
	 Lower order part of SIGMA

  QMAX	 (input) REAL
	 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 SLASQ5).