slasq5()

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.

Download SLASQ5 + dependencies [TGZ] [ZIP] [TXT]

Purpose:

 SLASQ5 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 REAL 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 REAL This is the shift.
[in]	SIGMA	SIGMA is REAL This is the accumulated shift up to this step.
[out]	DMIN	DMIN is REAL Minimum value of d.
[out]	DMIN1	DMIN1 is REAL Minimum value of d, excluding D( N0 ).
[out]	DMIN2	DMIN2 is REAL Minimum value of d, excluding D( N0 ) and D( N0-1 ).
[out]	DN	DN is REAL d(N0), the last value of d.
[out]	DNM1	DNM1 is REAL d(N0-1).
[out]	DNM2	DNM2 is REAL d(N0-2).
[in]	IEEE	IEEE is LOGICAL Flag for IEEE or non IEEE arithmetic.
[in]	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.

Definition at line 144 of file slasq5.f.