SRC/slasq6.f(3) Library Functions Manual SRC/slasq6.f(3)

SRC/slasq6.f


subroutine slasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2)
SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

Purpose:

!>
!> SLASQ6 computes one dqd (shift equal to zero) transform in
!> ping-pong form, with protection against underflow and overflow.
!> 

Parameters

I0
!>          I0 is INTEGER
!>        First index.
!> 

N0

!>          N0 is INTEGER
!>        Last index.
!> 

Z

!>          Z is REAL array, dimension ( 4*N )
!>        Z holds the qd array. EMIN is stored in Z(4*N0) to avoid
!>        an extra argument.
!> 

PP

!>          PP is INTEGER
!>        PP=0 for ping, PP=1 for pong.
!> 

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

!>          DN is REAL
!>        d(N0), the last value of d.
!> 

DNM1

!>          DNM1 is REAL
!>        d(N0-1).
!> 

DNM2

!>          DNM2 is REAL
!>        d(N0-2).
!> 

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 117 of file slasq6.f.

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