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1 207 jeremybenn
 
2
/* @(#)e_j0.c 5.1 93/09/24 */
3
/*
4
 * ====================================================
5
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6
 *
7
 * Developed at SunPro, a Sun Microsystems, Inc. business.
8
 * Permission to use, copy, modify, and distribute this
9
 * software is freely granted, provided that this notice
10
 * is preserved.
11
 * ====================================================
12
 */
13
 
14
/* __ieee754_j0(x), __ieee754_y0(x)
15
 * Bessel function of the first and second kinds of order zero.
16
 * Method -- j0(x):
17
 *      1. For tiny x, we use j0(x) = 1 - x^2/4 + x^4/64 - ...
18
 *      2. Reduce x to |x| since j0(x)=j0(-x),  and
19
 *         for x in (0,2)
20
 *              j0(x) = 1-z/4+ z^2*R0/S0,  where z = x*x;
21
 *         (precision:  |j0-1+z/4-z^2R0/S0 |<2**-63.67 )
22
 *         for x in (2,inf)
23
 *              j0(x) = sqrt(2/(pi*x))*(p0(x)*cos(x0)-q0(x)*sin(x0))
24
 *         where x0 = x-pi/4. It is better to compute sin(x0),cos(x0)
25
 *         as follow:
26
 *              cos(x0) = cos(x)cos(pi/4)+sin(x)sin(pi/4)
27
 *                      = 1/sqrt(2) * (cos(x) + sin(x))
28
 *              sin(x0) = sin(x)cos(pi/4)-cos(x)sin(pi/4)
29
 *                      = 1/sqrt(2) * (sin(x) - cos(x))
30
 *         (To avoid cancellation, use
31
 *              sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
32
 *          to compute the worse one.)
33
 *
34
 *      3 Special cases
35
 *              j0(nan)= nan
36
 *              j0(0) = 1
37
 *              j0(inf) = 0
38
 *
39
 * Method -- y0(x):
40
 *      1. For x<2.
41
 *         Since
42
 *              y0(x) = 2/pi*(j0(x)*(ln(x/2)+Euler) + x^2/4 - ...)
43
 *         therefore y0(x)-2/pi*j0(x)*ln(x) is an even function.
44
 *         We use the following function to approximate y0,
45
 *              y0(x) = U(z)/V(z) + (2/pi)*(j0(x)*ln(x)), z= x^2
46
 *         where
47
 *              U(z) = u00 + u01*z + ... + u06*z^6
48
 *              V(z) = 1  + v01*z + ... + v04*z^4
49
 *         with absolute approximation error bounded by 2**-72.
50
 *         Note: For tiny x, U/V = u0 and j0(x)~1, hence
51
 *              y0(tiny) = u0 + (2/pi)*ln(tiny), (choose tiny<2**-27)
52
 *      2. For x>=2.
53
 *              y0(x) = sqrt(2/(pi*x))*(p0(x)*cos(x0)+q0(x)*sin(x0))
54
 *         where x0 = x-pi/4. It is better to compute sin(x0),cos(x0)
55
 *         by the method mentioned above.
56
 *      3. Special cases: y0(0)=-inf, y0(x<0)=NaN, y0(inf)=0.
57
 */
58
 
59
#include "fdlibm.h"
60
 
61
#ifndef _DOUBLE_IS_32BITS
62
 
63
#ifdef __STDC__
64
static double pzero(double), qzero(double);
65
#else
66
static double pzero(), qzero();
67
#endif
68
 
69
#ifdef __STDC__
70
static const double
71
#else
72
static double
73
#endif
74
huge    = 1e300,
75
one     = 1.0,
76
invsqrtpi=  5.64189583547756279280e-01, /* 0x3FE20DD7, 0x50429B6D */
77
tpi      =  6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
78
                /* R0/S0 on [0, 2.00] */
79
R02  =  1.56249999999999947958e-02, /* 0x3F8FFFFF, 0xFFFFFFFD */
80
R03  = -1.89979294238854721751e-04, /* 0xBF28E6A5, 0xB61AC6E9 */
81
R04  =  1.82954049532700665670e-06, /* 0x3EBEB1D1, 0x0C503919 */
82
R05  = -4.61832688532103189199e-09, /* 0xBE33D5E7, 0x73D63FCE */
83
S01  =  1.56191029464890010492e-02, /* 0x3F8FFCE8, 0x82C8C2A4 */
84
S02  =  1.16926784663337450260e-04, /* 0x3F1EA6D2, 0xDD57DBF4 */
85
S03  =  5.13546550207318111446e-07, /* 0x3EA13B54, 0xCE84D5A9 */
86
S04  =  1.16614003333790000205e-09; /* 0x3E1408BC, 0xF4745D8F */
87
 
88
#ifdef __STDC__
89
static const double zero = 0.0;
90
#else
91
static double zero = 0.0;
92
#endif
93
 
94
#ifdef __STDC__
95
        double __ieee754_j0(double x)
96
#else
97
        double __ieee754_j0(x)
98
        double x;
99
#endif
100
{
101
        double z, s,c,ss,cc,r,u,v;
102
        __int32_t hx,ix;
103
 
104
        GET_HIGH_WORD(hx,x);
105
        ix = hx&0x7fffffff;
106
        if(ix>=0x7ff00000) return one/(x*x);
107
        x = fabs(x);
108
        if(ix >= 0x40000000) {  /* |x| >= 2.0 */
109
                s = sin(x);
110
                c = cos(x);
111
                ss = s-c;
112
                cc = s+c;
113
                if(ix<0x7fe00000) {  /* make sure x+x not overflow */
114
                    z = -cos(x+x);
115
                    if ((s*c)<zero) cc = z/ss;
116
                    else            ss = z/cc;
117
                }
118
        /*
119
         * j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x)
120
         * y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)
121
         */
122
                if(ix>0x48000000) z = (invsqrtpi*cc)/__ieee754_sqrt(x);
123
                else {
124
                    u = pzero(x); v = qzero(x);
125
                    z = invsqrtpi*(u*cc-v*ss)/__ieee754_sqrt(x);
126
                }
127
                return z;
128
        }
129
        if(ix<0x3f200000) {     /* |x| < 2**-13 */
130
            if(huge+x>one) {    /* raise inexact if x != 0 */
131
                if(ix<0x3e400000) return one;   /* |x|<2**-27 */
132
                else          return one - 0.25*x*x;
133
            }
134
        }
135
        z = x*x;
136
        r =  z*(R02+z*(R03+z*(R04+z*R05)));
137
        s =  one+z*(S01+z*(S02+z*(S03+z*S04)));
138
        if(ix < 0x3FF00000) {   /* |x| < 1.00 */
139
            return one + z*(-0.25+(r/s));
140
        } else {
141
            u = 0.5*x;
142
            return((one+u)*(one-u)+z*(r/s));
143
        }
144
}
145
 
146
#ifdef __STDC__
147
static const double
148
#else
149
static double
150
#endif
151
u00  = -7.38042951086872317523e-02, /* 0xBFB2E4D6, 0x99CBD01F */
152
u01  =  1.76666452509181115538e-01, /* 0x3FC69D01, 0x9DE9E3FC */
153
u02  = -1.38185671945596898896e-02, /* 0xBF8C4CE8, 0xB16CFA97 */
154
u03  =  3.47453432093683650238e-04, /* 0x3F36C54D, 0x20B29B6B */
155
u04  = -3.81407053724364161125e-06, /* 0xBECFFEA7, 0x73D25CAD */
156
u05  =  1.95590137035022920206e-08, /* 0x3E550057, 0x3B4EABD4 */
157
u06  = -3.98205194132103398453e-11, /* 0xBDC5E43D, 0x693FB3C8 */
158
v01  =  1.27304834834123699328e-02, /* 0x3F8A1270, 0x91C9C71A */
159
v02  =  7.60068627350353253702e-05, /* 0x3F13ECBB, 0xF578C6C1 */
160
v03  =  2.59150851840457805467e-07, /* 0x3E91642D, 0x7FF202FD */
161
v04  =  4.41110311332675467403e-10; /* 0x3DFE5018, 0x3BD6D9EF */
162
 
163
#ifdef __STDC__
164
        double __ieee754_y0(double x)
165
#else
166
        double __ieee754_y0(x)
167
        double x;
168
#endif
169
{
170
        double z, s,c,ss,cc,u,v;
171
        __int32_t hx,ix,lx;
172
 
173
        EXTRACT_WORDS(hx,lx,x);
174
        ix = 0x7fffffff&hx;
175
    /* Y0(NaN) is NaN, y0(-inf) is Nan, y0(inf) is 0  */
176
        if(ix>=0x7ff00000) return  one/(x+x*x);
177
        if((ix|lx)==0) return -one/zero;
178
        if(hx<0) return zero/zero;
179
        if(ix >= 0x40000000) {  /* |x| >= 2.0 */
180
        /* y0(x) = sqrt(2/(pi*x))*(p0(x)*sin(x0)+q0(x)*cos(x0))
181
         * where x0 = x-pi/4
182
         *      Better formula:
183
         *              cos(x0) = cos(x)cos(pi/4)+sin(x)sin(pi/4)
184
         *                      =  1/sqrt(2) * (sin(x) + cos(x))
185
         *              sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
186
         *                      =  1/sqrt(2) * (sin(x) - cos(x))
187
         * To avoid cancellation, use
188
         *              sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
189
         * to compute the worse one.
190
         */
191
                s = sin(x);
192
                c = cos(x);
193
                ss = s-c;
194
                cc = s+c;
195
        /*
196
         * j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x)
197
         * y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)
198
         */
199
                if(ix<0x7fe00000) {  /* make sure x+x not overflow */
200
                    z = -cos(x+x);
201
                    if ((s*c)<zero) cc = z/ss;
202
                    else            ss = z/cc;
203
                }
204
                if(ix>0x48000000) z = (invsqrtpi*ss)/__ieee754_sqrt(x);
205
                else {
206
                    u = pzero(x); v = qzero(x);
207
                    z = invsqrtpi*(u*ss+v*cc)/__ieee754_sqrt(x);
208
                }
209
                return z;
210
        }
211
        if(ix<=0x3e400000) {    /* x < 2**-27 */
212
            return(u00 + tpi*__ieee754_log(x));
213
        }
214
        z = x*x;
215
        u = u00+z*(u01+z*(u02+z*(u03+z*(u04+z*(u05+z*u06)))));
216
        v = one+z*(v01+z*(v02+z*(v03+z*v04)));
217
        return(u/v + tpi*(__ieee754_j0(x)*__ieee754_log(x)));
218
}
219
 
220
/* The asymptotic expansions of pzero is
221
 *      1 - 9/128 s^2 + 11025/98304 s^4 - ...,  where s = 1/x.
222
 * For x >= 2, We approximate pzero by
223
 *      pzero(x) = 1 + (R/S)
224
 * where  R = pR0 + pR1*s^2 + pR2*s^4 + ... + pR5*s^10
225
 *        S = 1 + pS0*s^2 + ... + pS4*s^10
226
 * and
227
 *      | pzero(x)-1-R/S | <= 2  ** ( -60.26)
228
 */
229
#ifdef __STDC__
230
static const double pR8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
231
#else
232
static double pR8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
233
#endif
234
  0.00000000000000000000e+00, /* 0x00000000, 0x00000000 */
235
 -7.03124999999900357484e-02, /* 0xBFB1FFFF, 0xFFFFFD32 */
236
 -8.08167041275349795626e+00, /* 0xC02029D0, 0xB44FA779 */
237
 -2.57063105679704847262e+02, /* 0xC0701102, 0x7B19E863 */
238
 -2.48521641009428822144e+03, /* 0xC0A36A6E, 0xCD4DCAFC */
239
 -5.25304380490729545272e+03, /* 0xC0B4850B, 0x36CC643D */
240
};
241
#ifdef __STDC__
242
static const double pS8[5] = {
243
#else
244
static double pS8[5] = {
245
#endif
246
  1.16534364619668181717e+02, /* 0x405D2233, 0x07A96751 */
247
  3.83374475364121826715e+03, /* 0x40ADF37D, 0x50596938 */
248
  4.05978572648472545552e+04, /* 0x40E3D2BB, 0x6EB6B05F */
249
  1.16752972564375915681e+05, /* 0x40FC810F, 0x8F9FA9BD */
250
  4.76277284146730962675e+04, /* 0x40E74177, 0x4F2C49DC */
251
};
252
 
253
#ifdef __STDC__
254
static const double pR5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
255
#else
256
static double pR5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
257
#endif
258
 -1.14125464691894502584e-11, /* 0xBDA918B1, 0x47E495CC */
259
 -7.03124940873599280078e-02, /* 0xBFB1FFFF, 0xE69AFBC6 */
260
 -4.15961064470587782438e+00, /* 0xC010A370, 0xF90C6BBF */
261
 -6.76747652265167261021e+01, /* 0xC050EB2F, 0x5A7D1783 */
262
 -3.31231299649172967747e+02, /* 0xC074B3B3, 0x6742CC63 */
263
 -3.46433388365604912451e+02, /* 0xC075A6EF, 0x28A38BD7 */
264
};
265
#ifdef __STDC__
266
static const double pS5[5] = {
267
#else
268
static double pS5[5] = {
269
#endif
270
  6.07539382692300335975e+01, /* 0x404E6081, 0x0C98C5DE */
271
  1.05125230595704579173e+03, /* 0x40906D02, 0x5C7E2864 */
272
  5.97897094333855784498e+03, /* 0x40B75AF8, 0x8FBE1D60 */
273
  9.62544514357774460223e+03, /* 0x40C2CCB8, 0xFA76FA38 */
274
  2.40605815922939109441e+03, /* 0x40A2CC1D, 0xC70BE864 */
275
};
276
 
277
#ifdef __STDC__
278
static const double pR3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
279
#else
280
static double pR3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
281
#endif
282
 -2.54704601771951915620e-09, /* 0xBE25E103, 0x6FE1AA86 */
283
 -7.03119616381481654654e-02, /* 0xBFB1FFF6, 0xF7C0E24B */
284
 -2.40903221549529611423e+00, /* 0xC00345B2, 0xAEA48074 */
285
 -2.19659774734883086467e+01, /* 0xC035F74A, 0x4CB94E14 */
286
 -5.80791704701737572236e+01, /* 0xC04D0A22, 0x420A1A45 */
287
 -3.14479470594888503854e+01, /* 0xC03F72AC, 0xA892D80F */
288
};
289
#ifdef __STDC__
290
static const double pS3[5] = {
291
#else
292
static double pS3[5] = {
293
#endif
294
  3.58560338055209726349e+01, /* 0x4041ED92, 0x84077DD3 */
295
  3.61513983050303863820e+02, /* 0x40769839, 0x464A7C0E */
296
  1.19360783792111533330e+03, /* 0x4092A66E, 0x6D1061D6 */
297
  1.12799679856907414432e+03, /* 0x40919FFC, 0xB8C39B7E */
298
  1.73580930813335754692e+02, /* 0x4065B296, 0xFC379081 */
299
};
300
 
301
#ifdef __STDC__
302
static const double pR2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
303
#else
304
static double pR2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
305
#endif
306
 -8.87534333032526411254e-08, /* 0xBE77D316, 0xE927026D */
307
 -7.03030995483624743247e-02, /* 0xBFB1FF62, 0x495E1E42 */
308
 -1.45073846780952986357e+00, /* 0xBFF73639, 0x8A24A843 */
309
 -7.63569613823527770791e+00, /* 0xC01E8AF3, 0xEDAFA7F3 */
310
 -1.11931668860356747786e+01, /* 0xC02662E6, 0xC5246303 */
311
 -3.23364579351335335033e+00, /* 0xC009DE81, 0xAF8FE70F */
312
};
313
#ifdef __STDC__
314
static const double pS2[5] = {
315
#else
316
static double pS2[5] = {
317
#endif
318
  2.22202997532088808441e+01, /* 0x40363865, 0x908B5959 */
319
  1.36206794218215208048e+02, /* 0x4061069E, 0x0EE8878F */
320
  2.70470278658083486789e+02, /* 0x4070E786, 0x42EA079B */
321
  1.53875394208320329881e+02, /* 0x40633C03, 0x3AB6FAFF */
322
  1.46576176948256193810e+01, /* 0x402D50B3, 0x44391809 */
323
};
324
 
325
#ifdef __STDC__
326
        static double pzero(double x)
327
#else
328
        static double pzero(x)
329
        double x;
330
#endif
331
{
332
#ifdef __STDC__
333
        const double *p,*q;
334
#else
335
        double *p,*q;
336
#endif
337
        double z,r,s;
338
        __int32_t ix;
339
        GET_HIGH_WORD(ix,x);
340
        ix &= 0x7fffffff;
341
        if(ix>=0x40200000)     {p = pR8; q= pS8;}
342
        else if(ix>=0x40122E8B){p = pR5; q= pS5;}
343
        else if(ix>=0x4006DB6D){p = pR3; q= pS3;}
344
      else {p = pR2; q= pS2;}
345
        z = one/(x*x);
346
        r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
347
        s = one+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*q[4]))));
348
        return one+ r/s;
349
}
350
 
351
 
352
/* For x >= 8, the asymptotic expansions of qzero is
353
 *      -1/8 s + 75/1024 s^3 - ..., where s = 1/x.
354
 * We approximate qzero by
355
 *      qzero(x) = s*(-1.25 + (R/S))
356
 * where  R = qR0 + qR1*s^2 + qR2*s^4 + ... + qR5*s^10
357
 *        S = 1 + qS0*s^2 + ... + qS5*s^12
358
 * and
359
 *      | qzero(x)/s +1.25-R/S | <= 2  ** ( -61.22)
360
 */
361
#ifdef __STDC__
362
static const double qR8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
363
#else
364
static double qR8[6] = { /* for x in [inf, 8]=1/[0,0.125] */
365
#endif
366
  0.00000000000000000000e+00, /* 0x00000000, 0x00000000 */
367
  7.32421874999935051953e-02, /* 0x3FB2BFFF, 0xFFFFFE2C */
368
  1.17682064682252693899e+01, /* 0x40278952, 0x5BB334D6 */
369
  5.57673380256401856059e+02, /* 0x40816D63, 0x15301825 */
370
  8.85919720756468632317e+03, /* 0x40C14D99, 0x3E18F46D */
371
  3.70146267776887834771e+04, /* 0x40E212D4, 0x0E901566 */
372
};
373
#ifdef __STDC__
374
static const double qS8[6] = {
375
#else
376
static double qS8[6] = {
377
#endif
378
  1.63776026895689824414e+02, /* 0x406478D5, 0x365B39BC */
379
  8.09834494656449805916e+03, /* 0x40BFA258, 0x4E6B0563 */
380
  1.42538291419120476348e+05, /* 0x41016652, 0x54D38C3F */
381
  8.03309257119514397345e+05, /* 0x412883DA, 0x83A52B43 */
382
  8.40501579819060512818e+05, /* 0x4129A66B, 0x28DE0B3D */
383
 -3.43899293537866615225e+05, /* 0xC114FD6D, 0x2C9530C5 */
384
};
385
 
386
#ifdef __STDC__
387
static const double qR5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
388
#else
389
static double qR5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
390
#endif
391
  1.84085963594515531381e-11, /* 0x3DB43D8F, 0x29CC8CD9 */
392
  7.32421766612684765896e-02, /* 0x3FB2BFFF, 0xD172B04C */
393
  5.83563508962056953777e+00, /* 0x401757B0, 0xB9953DD3 */
394
  1.35111577286449829671e+02, /* 0x4060E392, 0x0A8788E9 */
395
  1.02724376596164097464e+03, /* 0x40900CF9, 0x9DC8C481 */
396
  1.98997785864605384631e+03, /* 0x409F17E9, 0x53C6E3A6 */
397
};
398
#ifdef __STDC__
399
static const double qS5[6] = {
400
#else
401
static double qS5[6] = {
402
#endif
403
  8.27766102236537761883e+01, /* 0x4054B1B3, 0xFB5E1543 */
404
  2.07781416421392987104e+03, /* 0x40A03BA0, 0xDA21C0CE */
405
  1.88472887785718085070e+04, /* 0x40D267D2, 0x7B591E6D */
406
  5.67511122894947329769e+04, /* 0x40EBB5E3, 0x97E02372 */
407
  3.59767538425114471465e+04, /* 0x40E19118, 0x1F7A54A0 */
408
 -5.35434275601944773371e+03, /* 0xC0B4EA57, 0xBEDBC609 */
409
};
410
 
411
#ifdef __STDC__
412
static const double qR3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
413
#else
414
static double qR3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
415
#endif
416
  4.37741014089738620906e-09, /* 0x3E32CD03, 0x6ADECB82 */
417
  7.32411180042911447163e-02, /* 0x3FB2BFEE, 0x0E8D0842 */
418
  3.34423137516170720929e+00, /* 0x400AC0FC, 0x61149CF5 */
419
  4.26218440745412650017e+01, /* 0x40454F98, 0x962DAEDD */
420
  1.70808091340565596283e+02, /* 0x406559DB, 0xE25EFD1F */
421
  1.66733948696651168575e+02, /* 0x4064D77C, 0x81FA21E0 */
422
};
423
#ifdef __STDC__
424
static const double qS3[6] = {
425
#else
426
static double qS3[6] = {
427
#endif
428
  4.87588729724587182091e+01, /* 0x40486122, 0xBFE343A6 */
429
  7.09689221056606015736e+02, /* 0x40862D83, 0x86544EB3 */
430
  3.70414822620111362994e+03, /* 0x40ACF04B, 0xE44DFC63 */
431
  6.46042516752568917582e+03, /* 0x40B93C6C, 0xD7C76A28 */
432
  2.51633368920368957333e+03, /* 0x40A3A8AA, 0xD94FB1C0 */
433
 -1.49247451836156386662e+02, /* 0xC062A7EB, 0x201CF40F */
434
};
435
 
436
#ifdef __STDC__
437
static const double qR2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
438
#else
439
static double qR2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
440
#endif
441
  1.50444444886983272379e-07, /* 0x3E84313B, 0x54F76BDB */
442
  7.32234265963079278272e-02, /* 0x3FB2BEC5, 0x3E883E34 */
443
  1.99819174093815998816e+00, /* 0x3FFFF897, 0xE727779C */
444
  1.44956029347885735348e+01, /* 0x402CFDBF, 0xAAF96FE5 */
445
  3.16662317504781540833e+01, /* 0x403FAA8E, 0x29FBDC4A */
446
  1.62527075710929267416e+01, /* 0x403040B1, 0x71814BB4 */
447
};
448
#ifdef __STDC__
449
static const double qS2[6] = {
450
#else
451
static double qS2[6] = {
452
#endif
453
  3.03655848355219184498e+01, /* 0x403E5D96, 0xF7C07AED */
454
  2.69348118608049844624e+02, /* 0x4070D591, 0xE4D14B40 */
455
  8.44783757595320139444e+02, /* 0x408A6645, 0x22B3BF22 */
456
  8.82935845112488550512e+02, /* 0x408B977C, 0x9C5CC214 */
457
  2.12666388511798828631e+02, /* 0x406A9553, 0x0E001365 */
458
 -5.31095493882666946917e+00, /* 0xC0153E6A, 0xF8B32931 */
459
};
460
 
461
#ifdef __STDC__
462
        static double qzero(double x)
463
#else
464
        static double qzero(x)
465
        double x;
466
#endif
467
{
468
#ifdef __STDC__
469
        const double *p,*q;
470
#else
471
        double *p,*q;
472
#endif
473
        double s,r,z;
474
        __int32_t ix;
475
        GET_HIGH_WORD(ix,x);
476
        ix &= 0x7fffffff;
477
        if(ix>=0x40200000)     {p = qR8; q= qS8;}
478
        else if(ix>=0x40122E8B){p = qR5; q= qS5;}
479
        else if(ix>=0x4006DB6D){p = qR3; q= qS3;}
480
      else {p = qR2; q= qS2;}
481
        z = one/(x*x);
482
        r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
483
        s = one+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*(q[4]+z*q[5])))));
484
        return (-.125 + r/s)/x;
485
}
486
 
487
#endif /* defined(_DOUBLE_IS_32BITS) */

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