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CentOS 7.0 - man page for dlaed6 (centos section 3)

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)