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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