NAME

SRC/slasq4.f

SYNOPSIS

Functions/Subroutines

subroutine slasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)
SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Function/Subroutine Documentation

subroutine slasq4 (integer i0, integer n0, real, dimension( * ) z, integer pp, integer n0in, real dmin, real dmin1, real dmin2, real dn, real dn1, real dn2, real tau, integer ttype, real g)

SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Purpose:



 SLASQ4 computes an approximation TAU to the smallest eigenvalue


 using values of d from the previous transform.

Parameters



          I0 is INTEGER


        First index.



          N0 is INTEGER


        Last index.



          Z is REAL array, dimension ( 4*N0 )


        Z holds the qd array.



          PP is INTEGER


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

N0IN



          N0IN is INTEGER


        The value of N0 at start of EIGTEST.

DMIN



          DMIN is REAL


        Minimum value of d.

DMIN1



          DMIN1 is REAL


        Minimum value of d, excluding D( N0 ).

DMIN2



          DMIN2 is REAL


        Minimum value of d, excluding D( N0 ) and D( N0-1 ).



          DN is REAL


        d(N)

DN1



          DN1 is REAL


        d(N-1)

DN2



          DN2 is REAL


        d(N-2)

TAU



          TAU is REAL


        This is the shift.

TTYPE



          TTYPE is INTEGER


        Shift type.



          G is REAL


        G is passed as an argument in order to save its value between


        calls to SLASQ4.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:



  CNST1 = 9/16

Definition at line 149 of file slasq4.f.

Author

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