slasq5.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
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NAME

slasq5.f

SYNOPSIS

Functions/Subroutines

subroutine slasq5 (I0, N0, Z, PP, TAU, SIGMA, DMIN, DMIN1, DMIN2, DN, DNM1, DNM2, IEEE, EPS)
SLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

Function/Subroutine Documentation

subroutine slasq5 (integer I0, integer N0, real, dimension( * ) Z, integer PP, real TAU, real SIGMA, real DMIN, real DMIN1, real DMIN2, real DN, real DNM1, real DNM2, logical IEEE, real EPS)

SLASQ5 computes one dqds transform in ping-pong form. Used by sbdsqr and sstegr.

Purpose:

 SLASQ5 computes one dqds transform in ping-pong form, one
 version for IEEE machines another for non IEEE machines.

Parameters:

          I0 is INTEGER
        First index.

          N0 is INTEGER
        Last index.

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

TAU

          TAU is REAL
        This is the shift.

SIGMA

          SIGMA is REAL
        This is the accumulated shift up to this step.

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(N0), the last value of d.

DNM1

          DNM1 is REAL
        d(N0-1).

DNM2

          DNM2 is REAL
        d(N0-2).

IEEE

          IEEE is LOGICAL
        Flag for IEEE or non IEEE arithmetic.

EPS

         EPS is REAL
        This is the value of epsilon used.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

: December 2016

Definition at line 146 of file slasq5.f.

Author

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