Man page - lasq4(3)

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Manual

lasq4

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
subroutine dlasq4 (integer i0, integer n0, double precision, dimension( * )z, integer pp, integer n0in, double precision dmin, double precisiondmin1, double precision dmin2, double precision dn, double precisiondn1, double precision dn2, double precision tau, integer ttype, doubleprecision g)
subroutine slasq4 (integer i0, integer n0, real, dimension( * ) z, integerpp, integer n0in, real dmin, real dmin1, real dmin2, real dn, real dn1,real dn2, real tau, integer ttype, real g)
Author

NAME

lasq4 - lasq4: dqds step

SYNOPSIS

Functions

subroutine dlasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)
DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.
subroutine slasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)
SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Detailed Description

Function Documentation

subroutine dlasq4 (integer i0, integer n0, double precision, dimension( * )z, integer pp, integer n0in, double precision dmin, double precisiondmin1, double precision dmin2, double precision dn, double precisiondn1, double precision dn2, double precision tau, integer ttype, doubleprecision g)

DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Purpose:

DLASQ4 computes an approximation TAU to the smallest eigenvalue
using values of d from the previous transform.

Parameters

I0

I0 is INTEGER
First index.

N0

N0 is INTEGER
Last index.

Z

Z is DOUBLE PRECISION array, dimension ( 4*N0 )
Z holds the qd array.

PP

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

N0IN

N0IN is INTEGER
The value of N0 at start of EIGTEST.

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(N)

DN1

DN1 is DOUBLE PRECISION
d(N-1)

DN2

DN2 is DOUBLE PRECISION
d(N-2)

TAU

TAU is DOUBLE PRECISION
This is the shift.

TTYPE

TTYPE is INTEGER
Shift type.

G

G is DOUBLE PRECISION
G is passed as an argument in order to save its value between
calls to DLASQ4.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:

CNST1 = 9/16

subroutine slasq4 (integer i0, integer n0, real, dimension( * ) z, integerpp, integer n0in, real dmin, real dmin1, real dmin2, real dn, real dn1,real dn2, real tau, integer ttype, real g)

SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Purpose:

SLASQ4 computes an approximation TAU to the smallest eigenvalue
using values of d from the previous transform.

Parameters

I0

I0 is INTEGER
First index.

N0

N0 is INTEGER
Last index.

Z

Z is REAL array, dimension ( 4*N0 )
Z holds the qd array.

PP

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

N0IN

N0IN is INTEGER
The value of N0 at start of EIGTEST.

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

DN is REAL
d(N)

DN1

DN1 is REAL
d(N-1)

DN2

DN2 is REAL
d(N-2)

TAU

TAU is REAL
This is the shift.

TTYPE

TTYPE is INTEGER
Shift type.

G

G is REAL
G is passed as an argument in order to save its value between
calls to SLASQ4.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:

CNST1 = 9/16

Author

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