2. EL 7
  3. lapack
  4. DLASQ6(3)

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dlasq6.f(3) LAPACK dlasq6.f(3)

NAME

dlasq6.f -

SYNOPSIS

Functions/Subroutines


subroutine dlasq6 (I0, N0, Z, PP, DMIN, DMIN1, DMIN2, DN, DNM1, DNM2)
DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

Function/Subroutine Documentation

subroutine dlasq6 (integerI0, integerN0, double precision, dimension( * )Z, integerPP, double precisionDMIN, double precisionDMIN1, double precisionDMIN2, double precisionDN, double precisionDNM1, double precisionDNM2)

DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.

Purpose: 



 DLASQ6 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 DOUBLE PRECISION 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 DOUBLE PRECISION


        Minimum value of d.

DMIN1



          DMIN1 is DOUBLE PRECISION


        Minimum value of d, excluding D( N0 ).

DMIN2



          DMIN2 is DOUBLE PRECISION


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

DN



          DN is DOUBLE PRECISION


        d(N0), the last value of d.

DNM1



          DNM1 is DOUBLE PRECISION


        d(N0-1).

DNM2



          DNM2 is DOUBLE PRECISION


        d(N0-2).

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 119 of file dlasq6.f.

Author

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Tue Sep 25 2012 Version 3.4.2