Provided by: liblapack-doc_3.3.1-1_all #### NAME

```       LAPACK-3 - computes an approximation TAU to the smallest eigenvalue using values of d from
the previous transform

```

#### SYNOPSIS

```       SUBROUTINE DLASQ4( I0, N0, Z, PP, N0IN, DMIN, DMIN1, DMIN2, DN, DN1, DN2, TAU, TTYPE, G )

INTEGER        I0, N0, N0IN, PP, TTYPE

DOUBLE         PRECISION DMIN, DMIN1, DMIN2, DN, DN1, DN2, G, TAU

DOUBLE         PRECISION Z( * )

```

#### PURPOSE

```       DLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the
previous transform.

```

#### 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.

NOIN  (input) INTEGER
The value of N0 at start of EIGTEST.

DMIN  (input) DOUBLE PRECISION
Minimum value of d.
DMIN1 (input) DOUBLE PRECISION
Minimum value of d, excluding D( N0 ).
DMIN2 (input) DOUBLE PRECISION
Minimum value of d, excluding D( N0 ) and D( N0-1 ).

DN    (input) DOUBLE PRECISION
d(N)

DN1   (input) DOUBLE PRECISION
d(N-1)

DN2   (input) DOUBLE PRECISION
d(N-2)

TAU   (output) DOUBLE PRECISION
This is the shift.
TTYPE (output) INTEGER
Shift type.

G     (input/output) REAL
G is passed as an argument in order to save its value between
calls to DLASQ4.

```

#### FURTHERDETAILS

``` LAPACK routine (version 3.3.1)             April 2011                            DLASQ4(3lapack)
```