LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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dlasq6.f File Reference

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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 ( integer  I0,
integer  N0,
double precision, dimension( * )  Z,
integer  PP,
double precision  DMIN,
double precision  DMIN1,
double precision  DMIN2,
double precision  DN,
double precision  DNM1,
double precision  DNM2 
)

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

Download DLASQ6 + dependencies [TGZ] [ZIP] [TXT]
Purpose:
 DLASQ6 computes one dqd (shift equal to zero) transform in
 ping-pong form, with protection against underflow and overflow.
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.
[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).
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.

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