LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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dlasq5.f File Reference

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Functions/Subroutines

subroutine dlasq5 (I0, N0, Z, PP, TAU, SIGMA, DMIN, DMIN1, DMIN2, DN, DNM1, DNM2, IEEE, EPS)
 DLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

Function/Subroutine Documentation

subroutine dlasq5 ( integer  I0,
integer  N0,
double precision, dimension( * )  Z,
integer  PP,
double precision  TAU,
double precision  SIGMA,
double precision  DMIN,
double precision  DMIN1,
double precision  DMIN2,
double precision  DN,
double precision  DNM1,
double precision  DNM2,
logical  IEEE,
double precision  EPS 
)

DLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

Download DLASQ5 + dependencies [TGZ] [ZIP] [TXT]
Purpose:
 DLASQ5 computes one dqds transform in ping-pong form, one
 version for IEEE machines another for non IEEE machines.
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. EMIN is stored in Z(4*N0) to avoid
        an extra argument.
[in]PP
          PP is INTEGER
        PP=0 for ping, PP=1 for pong.
[in]TAU
          TAU is DOUBLE PRECISION
        This is the shift.
[in]SIGMA
          SIGMA is DOUBLE PRECISION
        This is the accumulated shift up to this step.
[out]DMIN
          DMIN is DOUBLE PRECISION
        Minimum value of d.
[out]DMIN1
          DMIN1 is DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ).
[out]DMIN2
          DMIN2 is DOUBLE PRECISION
        Minimum value of d, excluding D( N0 ) and D( N0-1 ).
[out]DN
          DN is DOUBLE PRECISION
        d(N0), the last value of d.
[out]DNM1
          DNM1 is DOUBLE PRECISION
        d(N0-1).
[out]DNM2
          DNM2 is DOUBLE PRECISION
        d(N0-2).
[in]IEEE
          IEEE is LOGICAL
        Flag for IEEE or non IEEE arithmetic.
[in]EPS
          EPS is DOUBLE PRECISION
        This is the value of epsilon used.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012

Definition at line 144 of file dlasq5.f.

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