dlaed6.f(3) LAPACK dlaed6.f(3)NAME
dlaed6.f -
SYNOPSIS
Functions/Subroutines
subroutine dlaed6 (KNITER, ORGATI, RHO, D, Z, FINIT, TAU, INFO)
DLAED6 used by sstedc. Computes one Newton step in solution of the
secular equation.
Function/Subroutine Documentation
subroutine dlaed6 (integerKNITER, logicalORGATI, double precisionRHO,
double precision, dimension( 3 )D, double precision, dimension( 3 )Z,
double precisionFINIT, double precisionTAU, integerINFO)
DLAED6 used by sstedc. Computes one Newton step in solution of the
secular equation.
Purpose:
DLAED6 computes the positive or negative root (closest to the origin)
of
z(1)z(2)z(3)f(x) = rho + --------- + ---------- + ---------
d(1)-x d(2)-x d(3)-x
It is assumed that
if ORGATI = .true. the root is between d(2) and d(3);
otherwise it is between d(1) and d(2)
This routine will be called by DLAED4 when necessary. In most cases,
the root sought is the smallest in magnitude, though it might not be
in some extremely rare situations.
Parameters:
KNITER
KNITER is INTEGER
Refer to DLAED4 for its significance.
ORGATI
ORGATI is LOGICAL
If ORGATI is true, the needed root is between d(2) and
d(3); otherwise it is between d(1) and d(2). See
DLAED4 for further details.
RHO
RHO is DOUBLE PRECISION
Refer to the equation f(x) above.
D
D is DOUBLE PRECISION array, dimension (3)
D satisfies d(1) < d(2) < d(3).
Z
Z is DOUBLE PRECISION array, dimension (3)
Each of the elements in z must be positive.
FINIT
FINIT is DOUBLE PRECISION
The value of f at 0. It is more accurate than the one
evaluated inside this routine (if someone wants to do
so).
TAU
TAU is DOUBLE PRECISION
The root of the equation f(x).
INFO
INFO is INTEGER
= 0: successful exit
> 0: if INFO = 1, failure to converge
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Further Details:
10/02/03: This version has a few statements commented out for thread
safety (machine parameters are computed on each entry). SJH.
05/10/06: Modified from a new version of Ren-Cang Li, use
Gragg-Thornton-Warner cubic convergent scheme for better stability.
Contributors:
Ren-Cang Li, Computer Science Division, University of California at
Berkeley, USA
Definition at line 141 of file dlaed6.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dlaed6.f(3)
