/* $NetBSD: n_j1.c,v 1.7 2011/11/02 02:34:56 christos Exp $ */
/*-
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)j1.c 8.2 (Berkeley) 11/30/93";
#endif
#endif /* not lint */
/*
* 16 December 1992
* Minor modifications by Peter McIlroy to adapt non-IEEE architecture.
*/
/*
* ====================================================
* Copyright (C) 1992 by Sun Microsystems, Inc.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*
* ******************* WARNING ********************
* This is an alpha version of SunPro's FDLIBM (Freely
* Distributable Math Library) for IEEE double precision
* arithmetic. FDLIBM is a basic math library written
* in C that runs on machines that conform to IEEE
* Standard 754/854. This alpha version is distributed
* for testing purpose. Those who use this software
* should report any bugs to
*
*
[email protected]
*
* -- K.C. Ng, Oct 12, 1992
* ************************************************
*/
/* double j1(double x), y1(double x)
* Bessel function of the first and second kinds of order zero.
* Method -- j1(x):
* 1. For tiny x, we use j1(x) = x/2 - x^3/16 + x^5/384 - ...
* 2. Reduce x to |x| since j1(x)=-j1(-x), and
* for x in (0,2)
* j1(x) = x/2 + x*z*R0/S0, where z = x*x;
* (precision: |j1/x - 1/2 - R0/S0 |<2**-61.51 )
* for x in (2,inf)
* j1(x) = sqrt(2/(pi*x))*(p1(x)*cos(x1)-q1(x)*sin(x1))
* y1(x) = sqrt(2/(pi*x))*(p1(x)*sin(x1)+q1(x)*cos(x1))
* where x1 = x-3*pi/4. It is better to compute sin(x1),cos(x1)
* as follows:
* cos(x1) = cos(x)cos(3pi/4)+sin(x)sin(3pi/4)
* = 1/sqrt(2) * (sin(x) - cos(x))
* sin(x1) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
* = -1/sqrt(2) * (sin(x) + cos(x))
* (To avoid cancellation, use
* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
* to compute the worse one.)
*
* 3 Special cases
* j1(nan)= nan
* j1(0) = 0
* j1(inf) = 0
*
* Method -- y1(x):
* 1. screen out x<=0 cases: y1(0)=-inf, y1(x<0)=NaN
* 2. For x<2.
* Since
* y1(x) = 2/pi*(j1(x)*(ln(x/2)+Euler)-1/x-x/2+5/64*x^3-...)
* therefore y1(x)-2/pi*j1(x)*ln(x)-1/x is an odd function.
* We use the following function to approximate y1,
* y1(x) = x*U(z)/V(z) + (2/pi)*(j1(x)*ln(x)-1/x), z= x^2
* where for x in [0,2] (abs err less than 2**-65.89)
* U(z) = u0 + u1*z + ... + u4*z^4
* V(z) = 1 + v1*z + ... + v5*z^5
* Note: For tiny x, 1/x dominate y1 and hence
* y1(tiny) = -2/pi/tiny, (choose tiny<2**-54)
* 3. For x>=2.
* y1(x) = sqrt(2/(pi*x))*(p1(x)*sin(x1)+q1(x)*cos(x1))
* where x1 = x-3*pi/4. It is better to compute sin(x1),cos(x1)
* by method mentioned above.
*/
#include "mathimpl.h"
#include <float.h>
#include <errno.h>
#if defined(__vax__) || defined(tahoe)
#define _IEEE 0
#else
#define _IEEE 1
#define infnan(x) (0.0)
#endif
static double pone (double), qone (double);
static const double
huge = _HUGE,
zero = 0.0,
one = 1.0,
invsqrtpi= 5.641895835477562869480794515607725858441e-0001,
tpi = 0.636619772367581343075535053490057448,
/* R0/S0 on [0,2] */
r00 = -6.250000000000000020842322918309200910191e-0002,
r01 = 1.407056669551897148204830386691427791200e-0003,
r02 = -1.599556310840356073980727783817809847071e-0005,
r03 = 4.967279996095844750387702652791615403527e-0008,
s01 = 1.915375995383634614394860200531091839635e-0002,
s02 = 1.859467855886309024045655476348872850396e-0004,
s03 = 1.177184640426236767593432585906758230822e-0006,
s04 = 5.046362570762170559046714468225101016915e-0009,
s05 = 1.235422744261379203512624973117299248281e-0011;
#define two_129 6.80564733841876926e+038 /* 2^129 */
#define two_m54 5.55111512312578270e-017 /* 2^-54 */
double
j1(double x)
{
double z, s,c,ss,cc,r,u,v,y;
y = fabs(x);
if (!finite(x)) { /* Inf or NaN */
#if _IEEE
if (x != x)
return(x);
else
#endif
return (copysign(x, zero));
}
y = fabs(x);
if (y >= 2) { /* |x| >= 2.0 */
s = sin(y);
c = cos(y);
ss = -s-c;
cc = s-c;
if (y < .5*DBL_MAX) { /* make sure y+y not overflow */
z = cos(y+y);
if ((s*c)<zero) cc = z/ss;
else ss = z/cc;
}
/*
* j1(x) = 1/sqrt(pi) * (P(1,x)*cc - Q(1,x)*ss) / sqrt(x)
* y1(x) = 1/sqrt(pi) * (P(1,x)*ss + Q(1,x)*cc) / sqrt(x)
*/
#if !defined(__vax__) && !defined(tahoe)
if (y > two_129) /* x > 2^129 */
z = (invsqrtpi*cc)/sqrt(y);
else
#endif /* defined(__vax__) || defined(tahoe) */
{
u = pone(y); v = qone(y);
z = invsqrtpi*(u*cc-v*ss)/sqrt(y);
}
if (x < 0) return -z;
else return z;
}
if (y < 7.450580596923828125e-009) { /* |x|<2**-27 */
if(huge+x>one) return 0.5*x;/* inexact if x!=0 necessary */
}
z = x*x;
r = z*(r00+z*(r01+z*(r02+z*r03)));
s = one+z*(s01+z*(s02+z*(s03+z*(s04+z*s05))));
r *= x;
return (x*0.5+r/s);
}
static const double u0[5] = {
-1.960570906462389484206891092512047539632e-0001,
5.044387166398112572026169863174882070274e-0002,
-1.912568958757635383926261729464141209569e-0003,
2.352526005616105109577368905595045204577e-0005,
-9.190991580398788465315411784276789663849e-0008,
};
static const double v0[5] = {
1.991673182366499064031901734535479833387e-0002,
2.025525810251351806268483867032781294682e-0004,
1.356088010975162198085369545564475416398e-0006,
6.227414523646214811803898435084697863445e-0009,
1.665592462079920695971450872592458916421e-0011,
};
double
y1(double x)
{
double z, s, c, ss, cc, u, v;
/* if Y1(NaN) is NaN, Y1(-inf) is NaN, Y1(inf) is 0 */
if (!finite(x)) {
#if _IEEE
if (x < 0)
return(zero/zero);
else if (x > 0)
return (0);
else
return(x);
#else
return (infnan(EDOM));
#endif
}
if (x <= 0) {
#if _IEEE
if (x == 0) return -one/zero;
#endif
if(x == 0) return(infnan(-ERANGE));
#if _IEEE
return (zero/zero);
#else
return(infnan(EDOM));
#endif
}
if (x >= 2) { /* |x| >= 2.0 */
s = sin(x);
c = cos(x);
ss = -s-c;
cc = s-c;
if (x < .5 * DBL_MAX) { /* make sure x+x not overflow */
z = cos(x+x);
if ((s*c)>zero) cc = z/ss;
else ss = z/cc;
}
/* y1(x) = sqrt(2/(pi*x))*(p1(x)*sin(x0)+q1(x)*cos(x0))
* where x0 = x-3pi/4
* Better formula:
* cos(x0) = cos(x)cos(3pi/4)+sin(x)sin(3pi/4)
* = 1/sqrt(2) * (sin(x) - cos(x))
* sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
* = -1/sqrt(2) * (cos(x) + sin(x))
* To avoid cancellation, use
* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
* to compute the worse one.
*/
#if _IEEE
if (x>two_129) {
z = (invsqrtpi*ss)/sqrt(x);
} else
#endif
{
u = pone(x); v = qone(x);
z = invsqrtpi*(u*ss+v*cc)/sqrt(x);
}
return z;
}
if (x <= two_m54) { /* x < 2**-54 */
return (-tpi/x);
}
z = x*x;
u = u0[0]+z*(u0[1]+z*(u0[2]+z*(u0[3]+z*u0[4])));
v = one+z*(v0[0]+z*(v0[1]+z*(v0[2]+z*(v0[3]+z*v0[4]))));
return (x*(u/v) + tpi*(j1(x)*log(x)-one/x));
}
/* For x >= 8, the asymptotic expansions of pone is
* 1 + 15/128 s^2 - 4725/2^15 s^4 - ..., where s = 1/x.
* We approximate pone by
* pone(x) = 1 + (R/S)
* where R = pr0 + pr1*s^2 + pr2*s^4 + ... + pr5*s^10
* S = 1 + ps0*s^2 + ... + ps4*s^10
* and
* | pone(x)-1-R/S | <= 2 ** ( -60.06)
*/
static const double pr8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
0.0,
1.171874999999886486643746274751925399540e-0001,
1.323948065930735690925827997575471527252e+0001,
4.120518543073785433325860184116512799375e+0002,
3.874745389139605254931106878336700275601e+0003,
7.914479540318917214253998253147871806507e+0003,
};
static const double ps8[5] = {
1.142073703756784104235066368252692471887e+0002,
3.650930834208534511135396060708677099382e+0003,
3.695620602690334708579444954937638371808e+0004,
9.760279359349508334916300080109196824151e+0004,
3.080427206278887984185421142572315054499e+0004,
};
static const double pr5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
1.319905195562435287967533851581013807103e-0011,
1.171874931906140985709584817065144884218e-0001,
6.802751278684328781830052995333841452280e+0000,
1.083081829901891089952869437126160568246e+0002,
5.176361395331997166796512844100442096318e+0002,
5.287152013633375676874794230748055786553e+0002,
};
static const double ps5[5] = {
5.928059872211313557747989128353699746120e+0001,
9.914014187336144114070148769222018425781e+0002,
5.353266952914879348427003712029704477451e+0003,
7.844690317495512717451367787640014588422e+0003,
1.504046888103610723953792002716816255382e+0003,
};
static const double pr3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
3.025039161373736032825049903408701962756e-0009,
1.171868655672535980750284752227495879921e-0001,
3.932977500333156527232725812363183251138e+0000,
3.511940355916369600741054592597098912682e+0001,
9.105501107507812029367749771053045219094e+0001,
4.855906851973649494139275085628195457113e+0001,
};
static const double ps3[5] = {
3.479130950012515114598605916318694946754e+0001,
3.367624587478257581844639171605788622549e+0002,
1.046871399757751279180649307467612538415e+0003,
8.908113463982564638443204408234739237639e+0002,
1.037879324396392739952487012284401031859e+0002,
};
static const double pr2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
1.077108301068737449490056513753865482831e-0007,
1.171762194626833490512746348050035171545e-0001,
2.368514966676087902251125130227221462134e+0000,
1.224261091482612280835153832574115951447e+0001,
1.769397112716877301904532320376586509782e+0001,
5.073523125888185399030700509321145995160e+0000,
};
static const double ps2[5] = {
2.143648593638214170243114358933327983793e+0001,
1.252902271684027493309211410842525120355e+0002,
2.322764690571628159027850677565128301361e+0002,
1.176793732871470939654351793502076106651e+0002,
8.364638933716182492500902115164881195742e+0000,
};
static double
pone(double x)
{
const double *p,*q;
double z,r,s;
if (x >= 8.0) {p = pr8; q= ps8;}
else if (x >= 4.54545211791992188) {p = pr5; q= ps5;}
else if (x >= 2.85714149475097656) {p = pr3; q= ps3;}
else /* if (x >= 2.0) */ {p = pr2; q= ps2;}
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]))));
return (one + r/s);
}
/* For x >= 8, the asymptotic expansions of qone is
* 3/8 s - 105/1024 s^3 - ..., where s = 1/x.
* We approximate pone by
* qone(x) = s*(0.375 + (R/S))
* where R = qr1*s^2 + qr2*s^4 + ... + qr5*s^10
* S = 1 + qs1*s^2 + ... + qs6*s^12
* and
* | qone(x)/s -0.375-R/S | <= 2 ** ( -61.13)
*/
static const double qr8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
0.0,
-1.025390624999927207385863635575804210817e-0001,
-1.627175345445899724355852152103771510209e+0001,
-7.596017225139501519843072766973047217159e+0002,
-1.184980667024295901645301570813228628541e+0004,
-4.843851242857503225866761992518949647041e+0004,
};
static const double qs8[6] = {
1.613953697007229231029079421446916397904e+0002,
7.825385999233484705298782500926834217525e+0003,
1.338753362872495800748094112937868089032e+0005,
7.196577236832409151461363171617204036929e+0005,
6.666012326177764020898162762642290294625e+0005,
-2.944902643038346618211973470809456636830e+0005,
};
static const double qr5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
-2.089799311417640889742251585097264715678e-0011,
-1.025390502413754195402736294609692303708e-0001,
-8.056448281239359746193011295417408828404e+0000,
-1.836696074748883785606784430098756513222e+0002,
-1.373193760655081612991329358017247355921e+0003,
-2.612444404532156676659706427295870995743e+0003,
};
static const double qs5[6] = {
8.127655013843357670881559763225310973118e+0001,
1.991798734604859732508048816860471197220e+0003,
1.746848519249089131627491835267411777366e+0004,
4.985142709103522808438758919150738000353e+0004,
2.794807516389181249227113445299675335543e+0004,
-4.719183547951285076111596613593553911065e+0003,
};
static const double qr3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
-5.078312264617665927595954813341838734288e-0009,
-1.025378298208370901410560259001035577681e-0001,
-4.610115811394734131557983832055607679242e+0000,
-5.784722165627836421815348508816936196402e+0001,
-2.282445407376317023842545937526967035712e+0002,
-2.192101284789093123936441805496580237676e+0002,
};
static const double qs3[6] = {
4.766515503237295155392317984171640809318e+0001,
6.738651126766996691330687210949984203167e+0002,
3.380152866795263466426219644231687474174e+0003,
5.547729097207227642358288160210745890345e+0003,
1.903119193388108072238947732674639066045e+0003,
-1.352011914443073322978097159157678748982e+0002,
};
static const double qr2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
-1.783817275109588656126772316921194887979e-0007,
-1.025170426079855506812435356168903694433e-0001,
-2.752205682781874520495702498875020485552e+0000,
-1.966361626437037351076756351268110418862e+0001,
-4.232531333728305108194363846333841480336e+0001,
-2.137192117037040574661406572497288723430e+0001,
};
static const double qs2[6] = {
2.953336290605238495019307530224241335502e+0001,
2.529815499821905343698811319455305266409e+0002,
7.575028348686454070022561120722815892346e+0002,
7.393932053204672479746835719678434981599e+0002,
1.559490033366661142496448853793707126179e+0002,
-4.959498988226281813825263003231704397158e+0000,
};
static double
qone(double x)
{
const double *p,*q;
double s,r,z;
if (x >= 8.0) {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 >= 2.0) */ {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 (.375 + r/s)/x;
}
