LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
dlasq4.f File Reference

Go to the source code of this file.

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine DLASQ4 ( INTEGER  I0,
INTEGER  N0,
DOUBLE PRECISION, dimension( * )  Z,
INTEGER  PP,
INTEGER  N0IN,
DOUBLE PRECISION  DMIN,
DOUBLE PRECISION  DMIN1,
DOUBLE PRECISION  DMIN2,
DOUBLE PRECISION  DN,
DOUBLE PRECISION  DN1,
DOUBLE PRECISION  DN2,
DOUBLE PRECISION  TAU,
INTEGER  TTYPE,
DOUBLE PRECISION  G 
)

DLASQ4

Download DLASQ4 + dependencies [TGZ] [ZIP] [TXT]
Purpose:

 DLASQ4 computes an approximation TAU to the smallest eigenvalue
 using values of d from the previous transform.
 
Parameters:
[in]I0
          I0 is INTEGER
        First index.
 
[in]N0
          N0 is INTEGER
        Last index.
 
[in]Z
          Z is DOUBLE PRECISION array, dimension ( 4*N )
        Z holds the qd array.
 
[in]PP
          PP is INTEGER
        PP=0 for ping, PP=1 for pong.
 
[in]N0IN
          N0IN is INTEGER
        The value of N0 at start of EIGTEST.
 
[in]DMIN
          DMIN is DOUBLE PRECISION
        Minimum value of d.
 
[in]DMIN1
          DMIN1 is DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ).
 
[in]DMIN2
          DMIN2 is DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ) and D( N0-1 ).
 
[in]DN
          DN is DOUBLE PRECISION
        d(N)
 
[in]DN1
          DN1 is DOUBLE PRECISION
        d(N-1)
 
[in]DN2
          DN2 is DOUBLE PRECISION
        d(N-2)
 
[out]TAU
          TAU is DOUBLE PRECISION
        This is the shift.
 
[out]TTYPE
          TTYPE is INTEGER
        Shift type.
 
[in,out]G
          G is REAL
        G is passed as an argument in order to save its value between
        calls to DLASQ4.
 
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Further Details:

  CNST1 = 9/16
 

Definition at line 151 of file dlasq4.f.

Here is the caller graph for this function:

 All Files Functions