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.

I0

          I0 is INTEGER


         First index.

N0

          N0 is INTEGER


         Last index.

Z

          Z is REAL array, dimension ( 4*N0 )


         Z holds the qd array.

PP

          PP is INTEGER


         PP=0 for ping, PP=1 for pong.


         PP=2 indicates that flipping was applied to the Z array


         and that the initial tests for deflation should not be


         performed.

DMIN

          DMIN is REAL


         Minimum value of d.

SIGMA

          SIGMA is REAL


         Sum of shifts used in current segment.

DESIG

          DESIG is REAL


         Lower order part of SIGMA

QMAX

          QMAX is REAL


         Maximum value of q.

NFAIL

          NFAIL is INTEGER


         Increment NFAIL by 1 each time the shift was too big.

ITER

          ITER is INTEGER


         Increment ITER by 1 for each iteration.

NDIV

          NDIV is INTEGER


         Increment NDIV by 1 for each division.

IEEE

          IEEE is LOGICAL


         Flag for IEEE or non IEEE arithmetic (passed to SLASQ5).

TTYPE

          TTYPE is INTEGER


         Shift type.

DMIN1

          DMIN1 is REAL

DMIN2

          DMIN2 is REAL

DN

          DN is REAL

DN1

          DN1 is REAL

DN2

          DN2 is REAL

G

          G is REAL

TAU

          TAU is REAL


         These are passed as arguments in order to save their values


         between calls to SLASQ3.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

June 2016