Man page - lasq3(3)

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Manual

lasq3

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
subroutine dlasq3 (integer i0, integer n0, double precision, dimension( * )z, integer pp, double precision dmin, double precision sigma, doubleprecision desig, double precision qmax, integer nfail, integer iter,integer ndiv, logical ieee, integer ttype, double precision dmin1,double precision dmin2, double precision dn, double precision dn1,double precision dn2, double precision g, double precision tau)
subroutine slasq3 (integer i0, integer n0, real, dimension( * ) z, integerpp, real dmin, real sigma, real desig, real qmax, integer nfail,integer iter, integer ndiv, logical ieee, integer ttype, real dmin1,real dmin2, real dn, real dn1, real dn2, real g, real tau)
Author

NAME

lasq3 - lasq3: dqds step

SYNOPSIS

Functions

subroutine dlasq3 (i0, n0, z, pp, dmin, sigma, desig, qmax, nfail, iter, ndiv, ieee, ttype, dmin1, dmin2, dn, dn1, dn2, g, tau)
DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.
subroutine slasq3 (i0, n0, z, pp, dmin, sigma, desig, qmax, nfail, iter, ndiv, ieee, ttype, dmin1, dmin2, dn, dn1, dn2, g, tau)
SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Detailed Description

Function Documentation

subroutine dlasq3 (integer i0, integer n0, double precision, dimension( * )z, integer pp, double precision dmin, double precision sigma, doubleprecision desig, double precision qmax, integer nfail, integer iter,integer ndiv, logical ieee, integer ttype, double precision dmin1,double precision dmin2, double precision dn, double precision dn1,double precision dn2, double precision g, double precision tau)

DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Purpose:

DLASQ3 checks for deflation, computes a shift (TAU) and calls dqds.
In case of failure it changes shifts, and tries again until output
is positive.

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.
PP=2 indicates that flipping was applied to the Z array
and that the initial tests for deflation should not be
performed.

DMIN

DMIN is DOUBLE PRECISION
Minimum value of d.

SIGMA

SIGMA is DOUBLE PRECISION
Sum of shifts used in current segment.

DESIG

DESIG is DOUBLE PRECISION
Lower order part of SIGMA

QMAX

QMAX is DOUBLE PRECISION
Maximum value of q.

NFAIL

NFAIL is INTEGER
Increment NFAIL by 1 each time the shift was too big.

ITER

ITER is INTEGER
Increment ITER by 1 for each iteration.

NDIV

NDIV is INTEGER
Increment NDIV by 1 for each division.

IEEE

IEEE is LOGICAL
Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).

TTYPE

TTYPE is INTEGER
Shift type.

DMIN1

DMIN1 is DOUBLE PRECISION

DMIN2

DMIN2 is DOUBLE PRECISION

DN

DN is DOUBLE PRECISION

DN1

DN1 is DOUBLE PRECISION

DN2

DN2 is DOUBLE PRECISION

G

G is DOUBLE PRECISION

TAU

TAU is DOUBLE PRECISION

These are passed as arguments in order to save their values
between calls to DLASQ3.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine slasq3 (integer i0, integer n0, real, dimension( * ) z, integerpp, real dmin, real sigma, real desig, real qmax, integer nfail,integer iter, integer ndiv, logical ieee, integer ttype, real dmin1,real dmin2, real dn, real dn1, real dn2, real g, real tau)

SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Purpose:

SLASQ3 checks for deflation, computes a shift (TAU) and calls dqds.
In case of failure it changes shifts, and tries again until output
is positive.

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.
PP=2 indicates that flipping was applied to the Z array
and that the initial tests for deflation should not be
performed.

DMIN

DMIN is REAL
Minimum value of d.

SIGMA

SIGMA is REAL
Sum of shifts used in current segment.

DESIG

DESIG is REAL
Lower order part of SIGMA

QMAX

QMAX is REAL
Maximum value of q.

NFAIL

NFAIL is INTEGER
Increment NFAIL by 1 each time the shift was too big.

ITER

ITER is INTEGER
Increment ITER by 1 for each iteration.

NDIV

NDIV is INTEGER
Increment NDIV by 1 for each division.

IEEE

IEEE is LOGICAL
Flag for IEEE or non IEEE arithmetic (passed to SLASQ5).

TTYPE

TTYPE is INTEGER
Shift type.

DMIN1

DMIN1 is REAL

DMIN2

DMIN2 is REAL

DN

DN is REAL

DN1

DN1 is REAL

DN2

DN2 is REAL

G

G is REAL

TAU

TAU is REAL

These are passed as arguments in order to save their values
between calls to SLASQ3.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Author

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