445 lines
16 KiB
C
445 lines
16 KiB
C
/* $NetBSD: n_j0.c,v 1.6 2003/08/07 16:44:51 agc Exp $ */
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/*-
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)j0.c 8.2 (Berkeley) 11/30/93";
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#endif
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#endif /* not lint */
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/*
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* 16 December 1992
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* Minor modifications by Peter McIlroy to adapt non-IEEE architecture.
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*/
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/*
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* ====================================================
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* Copyright (C) 1992 by Sun Microsystems, Inc.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*
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* ******************* WARNING ********************
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* This is an alpha version of SunPro's FDLIBM (Freely
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* Distributable Math Library) for IEEE double precision
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* arithmetic. FDLIBM is a basic math library written
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* in C that runs on machines that conform to IEEE
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* Standard 754/854. This alpha version is distributed
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* for testing purpose. Those who use this software
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* should report any bugs to
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*
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* fdlibm-comments@sunpro.eng.sun.com
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*
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* -- K.C. Ng, Oct 12, 1992
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* ************************************************
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*/
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/* double j0(double x), y0(double x)
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* Bessel function of the first and second kinds of order zero.
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* Method -- j0(x):
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* 1. For tiny x, we use j0(x) = 1 - x^2/4 + x^4/64 - ...
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* 2. Reduce x to |x| since j0(x)=j0(-x), and
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* for x in (0,2)
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* j0(x) = 1-z/4+ z^2*R0/S0, where z = x*x;
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* (precision: |j0-1+z/4-z^2R0/S0 |<2**-63.67 )
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* for x in (2,inf)
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* j0(x) = sqrt(2/(pi*x))*(p0(x)*cos(x0)-q0(x)*sin(x0))
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* where x0 = x-pi/4. It is better to compute sin(x0),cos(x0)
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* as follow:
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* cos(x0) = cos(x)cos(pi/4)+sin(x)sin(pi/4)
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* = 1/sqrt(2) * (cos(x) + sin(x))
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* sin(x0) = sin(x)cos(pi/4)-cos(x)sin(pi/4)
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* = 1/sqrt(2) * (sin(x) - cos(x))
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* (To avoid cancellation, use
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* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
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* to compute the worse one.)
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*
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* 3 Special cases
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* j0(nan)= nan
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* j0(0) = 1
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* j0(inf) = 0
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*
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* Method -- y0(x):
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* 1. For x<2.
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* Since
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* y0(x) = 2/pi*(j0(x)*(ln(x/2)+Euler) + x^2/4 - ...)
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* therefore y0(x)-2/pi*j0(x)*ln(x) is an even function.
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* We use the following function to approximate y0,
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* y0(x) = U(z)/V(z) + (2/pi)*(j0(x)*ln(x)), z= x^2
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* where
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* U(z) = u0 + u1*z + ... + u6*z^6
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* V(z) = 1 + v1*z + ... + v4*z^4
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* with absolute approximation error bounded by 2**-72.
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* Note: For tiny x, U/V = u0 and j0(x)~1, hence
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* y0(tiny) = u0 + (2/pi)*ln(tiny), (choose tiny<2**-27)
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* 2. For x>=2.
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* y0(x) = sqrt(2/(pi*x))*(p0(x)*cos(x0)+q0(x)*sin(x0))
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* where x0 = x-pi/4. It is better to compute sin(x0),cos(x0)
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* by the method mentioned above.
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* 3. Special cases: y0(0)=-inf, y0(x<0)=NaN, y0(inf)=0.
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*/
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#include "mathimpl.h"
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#include <float.h>
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#include <errno.h>
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#if defined(__vax__) || defined(tahoe)
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#define _IEEE 0
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#else
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#define _IEEE 1
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#define infnan(x) (0.0)
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#endif
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static double pzero (double), qzero (double);
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static const double
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huge = 1e300,
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zero = 0.0,
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one = 1.0,
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invsqrtpi= 5.641895835477562869480794515607725858441e-0001,
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tpi = 0.636619772367581343075535053490057448,
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/* R0/S0 on [0, 2.00] */
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r02 = 1.562499999999999408594634421055018003102e-0002,
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r03 = -1.899792942388547334476601771991800712355e-0004,
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r04 = 1.829540495327006565964161150603950916854e-0006,
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r05 = -4.618326885321032060803075217804816988758e-0009,
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s01 = 1.561910294648900170180789369288114642057e-0002,
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s02 = 1.169267846633374484918570613449245536323e-0004,
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s03 = 5.135465502073181376284426245689510134134e-0007,
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s04 = 1.166140033337900097836930825478674320464e-0009;
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double
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j0(double x)
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{
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double z, s,c,ss,cc,r,u,v;
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if (!finite(x)) {
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if (_IEEE) return one/(x*x);
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else return (0);
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}
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x = fabs(x);
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if (x >= 2.0) { /* |x| >= 2.0 */
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s = sin(x);
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c = cos(x);
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ss = s-c;
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cc = s+c;
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if (x < .5 * DBL_MAX) { /* make sure x+x not overflow */
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z = -cos(x+x);
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if ((s*c)<zero) cc = z/ss;
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else ss = z/cc;
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}
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/*
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* j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x)
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* y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)
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*/
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if (_IEEE && x> 6.80564733841876927e+38) /* 2^129 */
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z = (invsqrtpi*cc)/sqrt(x);
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else {
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u = pzero(x); v = qzero(x);
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z = invsqrtpi*(u*cc-v*ss)/sqrt(x);
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}
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return z;
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}
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if (x < 1.220703125e-004) { /* |x| < 2**-13 */
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if (huge+x > one) { /* raise inexact if x != 0 */
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if (x < 7.450580596923828125e-009) /* |x|<2**-27 */
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return one;
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else return (one - 0.25*x*x);
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}
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}
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z = x*x;
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r = z*(r02+z*(r03+z*(r04+z*r05)));
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s = one+z*(s01+z*(s02+z*(s03+z*s04)));
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if (x < one) { /* |x| < 1.00 */
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return (one + z*(-0.25+(r/s)));
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} else {
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u = 0.5*x;
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return ((one+u)*(one-u)+z*(r/s));
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}
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}
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static const double
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u00 = -7.380429510868722527422411862872999615628e-0002,
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u01 = 1.766664525091811069896442906220827182707e-0001,
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u02 = -1.381856719455968955440002438182885835344e-0002,
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u03 = 3.474534320936836562092566861515617053954e-0004,
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u04 = -3.814070537243641752631729276103284491172e-0006,
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u05 = 1.955901370350229170025509706510038090009e-0008,
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u06 = -3.982051941321034108350630097330144576337e-0011,
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v01 = 1.273048348341237002944554656529224780561e-0002,
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v02 = 7.600686273503532807462101309675806839635e-0005,
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v03 = 2.591508518404578033173189144579208685163e-0007,
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v04 = 4.411103113326754838596529339004302243157e-0010;
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double
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y0(double x)
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{
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double z, s, c, ss, cc, u, v;
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/* Y0(NaN) is NaN, y0(-inf) is Nan, y0(inf) is 0 */
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if (!finite(x)) {
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if (_IEEE)
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return (one/(x+x*x));
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else
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return (0);
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}
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if (x == 0) {
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if (_IEEE) return (-one/zero);
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else return(infnan(-ERANGE));
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}
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if (x<0) {
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if (_IEEE) return (zero/zero);
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else return (infnan(EDOM));
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}
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if (x >= 2.00) { /* |x| >= 2.0 */
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/* y0(x) = sqrt(2/(pi*x))*(p0(x)*sin(x0)+q0(x)*cos(x0))
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* where x0 = x-pi/4
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* Better formula:
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* cos(x0) = cos(x)cos(pi/4)+sin(x)sin(pi/4)
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* = 1/sqrt(2) * (sin(x) + cos(x))
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* sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
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* = 1/sqrt(2) * (sin(x) - cos(x))
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* To avoid cancellation, use
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* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
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* to compute the worse one.
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*/
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s = sin(x);
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c = cos(x);
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ss = s-c;
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cc = s+c;
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/*
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* j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x)
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* y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)
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*/
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if (x < .5 * DBL_MAX) { /* make sure x+x not overflow */
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z = -cos(x+x);
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if ((s*c)<zero) cc = z/ss;
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else ss = z/cc;
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}
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if (_IEEE && x > 6.80564733841876927e+38) /* > 2^129 */
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z = (invsqrtpi*ss)/sqrt(x);
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else {
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u = pzero(x); v = qzero(x);
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z = invsqrtpi*(u*ss+v*cc)/sqrt(x);
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}
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return z;
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}
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if (x <= 7.450580596923828125e-009) { /* x < 2**-27 */
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return (u00 + tpi*log(x));
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}
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z = x*x;
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u = u00+z*(u01+z*(u02+z*(u03+z*(u04+z*(u05+z*u06)))));
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v = one+z*(v01+z*(v02+z*(v03+z*v04)));
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return (u/v + tpi*(j0(x)*log(x)));
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}
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/* The asymptotic expansions of pzero is
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* 1 - 9/128 s^2 + 11025/98304 s^4 - ..., where s = 1/x.
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* For x >= 2, We approximate pzero by
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* pzero(x) = 1 + (R/S)
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* where R = pr0 + pr1*s^2 + pr2*s^4 + ... + pr5*s^10
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* S = 1 + ps0*s^2 + ... + ps4*s^10
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* and
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* | pzero(x)-1-R/S | <= 2 ** ( -60.26)
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*/
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static const double pr8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
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0.0,
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-7.031249999999003994151563066182798210142e-0002,
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-8.081670412753498508883963849859423939871e+0000,
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-2.570631056797048755890526455854482662510e+0002,
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-2.485216410094288379417154382189125598962e+0003,
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-5.253043804907295692946647153614119665649e+0003,
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};
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static const double ps8[5] = {
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1.165343646196681758075176077627332052048e+0002,
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3.833744753641218451213253490882686307027e+0003,
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4.059785726484725470626341023967186966531e+0004,
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1.167529725643759169416844015694440325519e+0005,
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4.762772841467309430100106254805711722972e+0004,
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};
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static const double pr5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
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-1.141254646918944974922813501362824060117e-0011,
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-7.031249408735992804117367183001996028304e-0002,
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-4.159610644705877925119684455252125760478e+0000,
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-6.767476522651671942610538094335912346253e+0001,
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-3.312312996491729755731871867397057689078e+0002,
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-3.464333883656048910814187305901796723256e+0002,
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};
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static const double ps5[5] = {
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6.075393826923003305967637195319271932944e+0001,
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1.051252305957045869801410979087427910437e+0003,
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5.978970943338558182743915287887408780344e+0003,
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9.625445143577745335793221135208591603029e+0003,
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2.406058159229391070820491174867406875471e+0003,
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};
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static const double pr3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
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-2.547046017719519317420607587742992297519e-0009,
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-7.031196163814817199050629727406231152464e-0002,
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-2.409032215495295917537157371488126555072e+0000,
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-2.196597747348830936268718293366935843223e+0001,
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-5.807917047017375458527187341817239891940e+0001,
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-3.144794705948885090518775074177485744176e+0001,
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};
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static const double ps3[5] = {
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3.585603380552097167919946472266854507059e+0001,
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3.615139830503038919981567245265266294189e+0002,
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1.193607837921115243628631691509851364715e+0003,
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1.127996798569074250675414186814529958010e+0003,
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1.735809308133357510239737333055228118910e+0002,
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};
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static const double pr2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
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-8.875343330325263874525704514800809730145e-0008,
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-7.030309954836247756556445443331044338352e-0002,
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-1.450738467809529910662233622603401167409e+0000,
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-7.635696138235277739186371273434739292491e+0000,
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-1.119316688603567398846655082201614524650e+0001,
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-3.233645793513353260006821113608134669030e+0000,
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};
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static const double ps2[5] = {
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2.222029975320888079364901247548798910952e+0001,
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1.362067942182152109590340823043813120940e+0002,
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2.704702786580835044524562897256790293238e+0002,
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1.538753942083203315263554770476850028583e+0002,
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1.465761769482561965099880599279699314477e+0001,
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};
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static double
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pzero(double x)
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{
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const double *p,*q;
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double z,r,s;
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if (x >= 8.00) {p = pr8; q= ps8;}
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else if (x >= 4.54545211791992188) {p = pr5; q= ps5;}
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else if (x >= 2.85714149475097656) {p = pr3; q= ps3;}
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else /* if (x >= 2.00) */ {p = pr2; q= ps2;}
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z = one/(x*x);
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r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
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s = one+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*q[4]))));
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return one+ r/s;
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}
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/* For x >= 8, the asymptotic expansions of qzero is
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* -1/8 s + 75/1024 s^3 - ..., where s = 1/x.
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* We approximate pzero by
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* qzero(x) = s*(-1.25 + (R/S))
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* where R = qr0 + qr1*s^2 + qr2*s^4 + ... + qr5*s^10
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* S = 1 + qs0*s^2 + ... + qs5*s^12
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* and
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* | qzero(x)/s +1.25-R/S | <= 2 ** ( -61.22)
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*/
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static const double qr8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
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0.0,
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7.324218749999350414479738504551775297096e-0002,
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1.176820646822526933903301695932765232456e+0001,
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5.576733802564018422407734683549251364365e+0002,
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8.859197207564685717547076568608235802317e+0003,
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3.701462677768878501173055581933725704809e+0004,
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};
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static const double qs8[6] = {
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1.637760268956898345680262381842235272369e+0002,
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8.098344946564498460163123708054674227492e+0003,
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1.425382914191204905277585267143216379136e+0005,
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8.033092571195144136565231198526081387047e+0005,
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8.405015798190605130722042369969184811488e+0005,
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-3.438992935378666373204500729736454421006e+0005,
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};
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static const double qr5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
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1.840859635945155400568380711372759921179e-0011,
|
|
7.324217666126847411304688081129741939255e-0002,
|
|
5.835635089620569401157245917610984757296e+0000,
|
|
1.351115772864498375785526599119895942361e+0002,
|
|
1.027243765961641042977177679021711341529e+0003,
|
|
1.989977858646053872589042328678602481924e+0003,
|
|
};
|
|
static const double qs5[6] = {
|
|
8.277661022365377058749454444343415524509e+0001,
|
|
2.077814164213929827140178285401017305309e+0003,
|
|
1.884728877857180787101956800212453218179e+0004,
|
|
5.675111228949473657576693406600265778689e+0004,
|
|
3.597675384251145011342454247417399490174e+0004,
|
|
-5.354342756019447546671440667961399442388e+0003,
|
|
};
|
|
|
|
static const double qr3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
|
|
4.377410140897386263955149197672576223054e-0009,
|
|
7.324111800429115152536250525131924283018e-0002,
|
|
3.344231375161707158666412987337679317358e+0000,
|
|
4.262184407454126175974453269277100206290e+0001,
|
|
1.708080913405656078640701512007621675724e+0002,
|
|
1.667339486966511691019925923456050558293e+0002,
|
|
};
|
|
static const double qs3[6] = {
|
|
4.875887297245871932865584382810260676713e+0001,
|
|
7.096892210566060535416958362640184894280e+0002,
|
|
3.704148226201113687434290319905207398682e+0003,
|
|
6.460425167525689088321109036469797462086e+0003,
|
|
2.516333689203689683999196167394889715078e+0003,
|
|
-1.492474518361563818275130131510339371048e+0002,
|
|
};
|
|
|
|
static const double qr2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
|
|
1.504444448869832780257436041633206366087e-0007,
|
|
7.322342659630792930894554535717104926902e-0002,
|
|
1.998191740938159956838594407540292600331e+0000,
|
|
1.449560293478857407645853071687125850962e+0001,
|
|
3.166623175047815297062638132537957315395e+0001,
|
|
1.625270757109292688799540258329430963726e+0001,
|
|
};
|
|
static const double qs2[6] = {
|
|
3.036558483552191922522729838478169383969e+0001,
|
|
2.693481186080498724211751445725708524507e+0002,
|
|
8.447837575953201460013136756723746023736e+0002,
|
|
8.829358451124885811233995083187666981299e+0002,
|
|
2.126663885117988324180482985363624996652e+0002,
|
|
-5.310954938826669402431816125780738924463e+0000,
|
|
};
|
|
|
|
static double
|
|
qzero(double x)
|
|
{
|
|
const double *p,*q;
|
|
double s,r,z;
|
|
if (x >= 8.00) {p = qr8; q= qs8;}
|
|
else if (x >= 4.54545211791992188) {p = qr5; q= qs5;}
|
|
else if (x >= 2.85714149475097656) {p = qr3; q= qs3;}
|
|
else /* if (x >= 2.00) */ {p = qr2; q= qs2;}
|
|
z = one/(x*x);
|
|
r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
|
|
s = one+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*(q[4]+z*q[5])))));
|
|
return (-.125 + r/s)/x;
|
|
}
|