1 /* e_j0f.c -- float version of e_j0.c.
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 * Developed at SunPro, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
12 * ====================================================
16 #include <math-barriers.h>
17 #include <math_private.h>
18 #include <fenv_private.h>
19 #include <libm-alias-finite.h>
20 #include <reduce_aux.h>
22 static float pzerof(float), qzerof(float);
27 invsqrtpi
= 5.6418961287e-01, /* 0x3f106ebb */
28 tpi
= 6.3661974669e-01, /* 0x3f22f983 */
29 /* R0/S0 on [0, 2.00] */
30 R02
= 1.5625000000e-02, /* 0x3c800000 */
31 R03
= -1.8997929874e-04, /* 0xb947352e */
32 R04
= 1.8295404516e-06, /* 0x35f58e88 */
33 R05
= -4.6183270541e-09, /* 0xb19eaf3c */
34 S01
= 1.5619102865e-02, /* 0x3c7fe744 */
35 S02
= 1.1692678527e-04, /* 0x38f53697 */
36 S03
= 5.1354652442e-07, /* 0x3509daa6 */
37 S04
= 1.1661400734e-09; /* 0x30a045e8 */
39 static const float zero
= 0.0;
41 /* This is the nearest approximation of the first zero of j0. */
42 #define FIRST_ZERO_J0 0x1.33d152p+1f
46 /* The following table contains successive zeros of j0 and degree-3
47 polynomial approximations of j0 around these zeros: Pj[0] for the first
48 zero (2.40482), Pj[1] for the second one (5.520078), and so on.
50 {x0, xmid, x1, p0, p1, p2, p3}
51 where [x0,x1] is the interval around the zero, xmid is the binary32 number
52 closest to the zero, and p0+p1*x+p2*x^2+p3*x^3 is the approximation
53 polynomial. Each polynomial was generated using Sollya on the interval
54 [x0,x1] around the corresponding zero where the error exceeds 9 ulps
55 for the alternate code. Degree 3 is enough to get an error <= 9 ulps.
57 static const float Pj
[SMALL_SIZE
][7] = {
58 /* The following polynomial was optimized by hand with respect to the one
59 generated by Sollya, to ensure the maximal error is at most 9 ulps,
60 both if the polynomial is evaluated with fma or not. */
61 { 0x1.31e5c4p
+1, 0x1.33d152p
+1, 0x1.3b58dep
+1, 0xf.2623fp
-28,
62 -0x8.4e6d7p
-4, 0x1.ba2aaap
-4, 0xe.4b9ap
-8 }, /* 0 */
63 { 0x1.60eafap
+2, 0x1.6148f6p
+2, 0x1.62955cp
+2, 0x6.9205fp
-28,
64 0x5.71b98p
-4, -0x7.e3e798p
-8, -0xd.87d1p
-8 }, /* 1 */
65 { 0x1.14cde2p
+3, 0x1.14eb56p
+3, 0x1.1525c6p
+3, 0x1.bcc1cap
-24,
66 -0x4.57de6p
-4, 0x4.03e7cp
-8, 0xb.39a37p
-8 }, /* 2 */
67 { 0x1.7931d8p
+3, 0x1.79544p
+3, 0x1.7998d6p
+3, -0xf.2976fp
-32,
68 0x3.b827ccp
-4, -0x2.8603ep
-8, -0x9.bf49bp
-8 }, /* 3 */
69 { 0x1.ddb6d4p
+3, 0x1.ddca14p
+3, 0x1.ddf0c8p
+3, -0x1.bd67d8p
-28,
70 -0x3.4e03ap
-4, 0x1.c562a2p
-8, 0x8.90ec2p
-8 }, /* 4 */
71 { 0x1.2118e4p
+4, 0x1.212314p
+4, 0x1.21375p
+4, 0x1.62209cp
-28,
72 0x3.00efecp
-4, -0x1.5458dap
-8, -0x8.10063p
-8 }, /* 5 */
73 { 0x1.535d28p
+4, 0x1.5362dep
+4, 0x1.536e48p
+4, -0x2.853f74p
-24,
74 -0x2.c5b274p
-4, 0x1.0b9db4p
-8, 0x7.8c3578p
-8 }, /* 6 */
75 { 0x1.859ddp
+4, 0x1.85a3bap
+4, 0x1.85aff4p
+4, 0x2.19ed1cp
-24,
76 0x2.96545cp
-4, -0xd.997e6p
-12, -0x6.d9af28p
-8 }, /* 7 */
77 { 0x1.b7decap
+4, 0x1.b7e54ap
+4, 0x1.b7f038p
+4, 0xe.959aep
-28,
78 -0x2.6f5594p
-4, 0xb.538dp
-12, 0x7.003ea8p
-8 }, /* 8 */
79 { 0x1.ea21c6p
+4, 0x1.ea275ap
+4, 0x1.ea337ap
+4, 0x2.0c3964p
-24,
80 0x2.4e80fcp
-4, -0x9.a2216p
-12, -0x6.61e0a8p
-8 }, /* 9 */
81 { 0x1.0e3316p
+5, 0x1.0e34e2p
+5, 0x1.0e379ap
+5, -0x3.642554p
-24,
82 -0x2.325e48p
-4, 0x8.4f49cp
-12, 0x7.d37c3p
-8 }, /* 10 */
83 { 0x1.275456p
+5, 0x1.275638p
+5, 0x1.2759e2p
+5, 0x1.6c015ap
-24,
84 0x2.19e7d8p
-4, -0x7.4c1bf8p
-12, -0x4.af7ef8p
-8 }, /* 11 */
85 { 0x1.4075ecp
+5, 0x1.4077a8p
+5, 0x1.407b96p
+5, -0x4.b18c9p
-28,
86 -0x2.046174p
-4, 0x6.705618p
-12, 0x5.f2d28p
-8 }, /* 12 */
87 { 0x1.59973p
+5, 0x1.59992cp
+5, 0x1.599b2ap
+5, -0x1.8b8792p
-24,
88 0x1.f13fbp
-4, -0x5.c14938p
-12, -0x5.73e0cp
-8 }, /* 13 */
89 { 0x1.72b958p
+5, 0x1.72bacp
+5, 0x1.72bc5ap
+5, 0x3.a26e0cp
-24,
90 -0x1.e018dap
-4, 0x5.30e8dp
-12, 0x2.81099p
-8 }, /* 14 */
91 { 0x1.8bdb4ap
+5, 0x1.8bdc62p
+5, 0x1.8bde7ep
+5, -0x2.18fabcp
-24,
92 0x1.d09b22p
-4, -0x4.b0b688p
-12, -0x5.5fd308p
-8 }, /* 15 */
93 { 0x1.a4fcecp
+5, 0x1.a4fe0ep
+5, 0x1.a50042p
+5, 0x3.2370e8p
-24,
94 -0x1.c28614p
-4, 0x4.4647e8p
-12, 0x5.68a28p
-8 }, /* 16 */
95 { 0x1.be1ebcp
+5, 0x1.be1fc4p
+5, 0x1.be21fp
+5, -0x5.9eae3p
-28,
96 0x1.b5a622p
-4, -0x3.eb9054p
-12, -0x5.12d8cp
-8 }, /* 17 */
97 { 0x1.d7405p
+5, 0x1.d7418p
+5, 0x1.d74294p
+5, 0x2.9fa1e8p
-24,
98 -0x1.a9d184p
-4, 0x3.9d1e7p
-12, 0x4.33d058p
-8 }, /* 18 */
99 { 0x1.f0624p
+5, 0x1.f06344p
+5, 0x1.f0645ep
+5, 0x9.9ac67p
-28,
100 0x1.9ee5eep
-4, -0x3.5816e8p
-12, -0x2.6e5004p
-8 }, /* 19 */
101 { 0x1.04c22ep
+6, 0x1.04c286p
+6, 0x1.04c316p
+6, 0xd.6ab94p
-28,
102 -0x1.94c6f6p
-4, 0x3.174efcp
-12, 0x7.9a092p
-8 }, /* 20 */
103 { 0x1.1153p
+6, 0x1.11536cp
+6, 0x1.11541p
+6, -0x4.4cb2d8p
-24,
104 0x1.8b5cccp
-4, -0x2.e3c238p
-12, -0x4.e5437p
-8 }, /* 21 */
105 { 0x1.1de3d8p
+6, 0x1.1de456p
+6, 0x1.1de4dap
+6, -0x4.4aa8c8p
-24,
106 -0x1.829356p
-4, 0x2.b45124p
-12, 0x5.baf638p
-8 }, /* 22 */
107 { 0x1.2a74f8p
+6, 0x1.2a754p
+6, 0x1.2a75bp
+6, 0x2.077c38p
-24,
108 0x1.7a597ep
-4, -0x2.8a0414p
-12, -0x2.838d3p
-8 }, /* 23 */
109 { 0x1.3705d4p
+6, 0x1.37062cp
+6, 0x1.3706b2p
+6, -0x2.6a6cd8p
-24,
110 -0x1.72a09ap
-4, 0x2.623a3cp
-12, 0x5.5256a8p
-8 }, /* 24 */
111 { 0x1.4396dp
+6, 0x1.439718p
+6, 0x1.43976ep
+6, -0x5.08287p
-24,
112 0x1.6b5c06p
-4, -0x2.3da154p
-12, -0x7.a2254p
-8 }, /* 25 */
113 { 0x1.5027acp
+6, 0x1.502808p
+6, 0x1.50288cp
+6, -0x3.4598dcp
-24,
114 -0x1.6480c4p
-4, 0x2.1cb944p
-12, 0x7.27c77p
-8 }, /* 26 */
115 { 0x1.5cb89ap
+6, 0x1.5cb8f8p
+6, 0x1.5cb97ep
+6, 0x5.4e74bp
-24,
116 0x1.5e0544p
-4, -0x2.00b158p
-12, -0x5.9bc4a8p
-8 }, /* 27 */
117 { 0x1.69498cp
+6, 0x1.6949e8p
+6, 0x1.694a42p
+6, -0x2.05751cp
-24,
118 -0x1.57e12p
-4, 0x1.e78edcp
-12, 0x9.9667dp
-8 }, /* 28 */
119 { 0x1.75da7ep
+6, 0x1.75dadap
+6, 0x1.75db3p
+6, 0x4.c5e278p
-24,
120 0x1.520ceep
-4, -0x1.d0127cp
-12, -0xd.62681p
-8 }, /* 29 */
121 { 0x1.826b7ep
+6, 0x1.826bccp
+6, 0x1.826c2cp
+6, -0x3.50e62cp
-24,
122 -0x1.4c822p
-4, 0x1.ba5832p
-12, -0x1.eb2ee2p
-8 }, /* 30 */
123 { 0x1.8efc84p
+6, 0x1.8efcbep
+6, 0x1.8efd16p
+6, -0x1.c39f38p
-24,
124 0x1.473ae6p
-4, -0x1.a616c8p
-12, 0xf.f352ap
-12 }, /* 31 */
125 { 0x1.9b8d84p
+6, 0x1.9b8db2p
+6, 0x1.9b8e7p
+6, -0x1.9245b6p
-28,
126 -0x1.42320ap
-4, 0x1.932a04p
-12, 0x2.dc113cp
-8 }, /* 32 */
127 { 0x1.a81e72p
+6, 0x1.a81ea6p
+6, 0x1.a81f04p
+6, -0x1.0acf8p
-24,
128 0x1.3d62e6p
-4, -0x1.7c4b14p
-12, -0x1.cfc5c2p
-4 }, /* 33 */
129 { 0x1.b4af6ap
+6, 0x1.b4af9ap
+6, 0x1.b4afeep
+6, 0x4.cd92d8p
-24,
130 -0x1.38c94ap
-4, 0x1.643154p
-12, 0x1.4c2a06p
-4 }, /* 34 */
131 { 0x1.c1406p
+6, 0x1.c1409p
+6, 0x1.c140cp
+6, -0x1.37bf8ap
-24,
132 0x1.34617p
-4, -0x1.5f504ap
-12, -0x1.e2d324p
-4 }, /* 35 */
133 { 0x1.cdd154p
+6, 0x1.cdd186p
+6, 0x1.cdd1eap
+6, -0x1.8f62dep
-28,
134 -0x1.3027fp
-4, 0x1.534a02p
-12, 0x2.c7f144p
-12 }, /* 36 */
135 { 0x1.da6248p
+6, 0x1.da627cp
+6, 0x1.da62e6p
+6, -0x9.81e79p
-28,
136 0x1.2c19b4p
-4, -0x1.4b8288p
-12, 0x7.2d8bap
-8 }, /* 37 */
137 { 0x1.e6f33ep
+6, 0x1.e6f372p
+6, 0x1.e6f3a8p
+6, 0x3.103b3p
-24,
138 -0x1.2833eep
-4, 0x1.36f4d2p
-12, 0x9.29f91p
-8 }, /* 38 */
139 { 0x1.f38434p
+6, 0x1.f3846ap
+6, 0x1.f384d8p
+6, 0x2.07b058p
-24,
140 0x1.24740ap
-4, -0x1.2ee58ap
-12, 0xd.f1393p
-12 }, /* 39 */
141 { 0x1.000a98p
+7, 0x1.000abp
+7, 0x1.000ac8p
+7, 0x3.87576cp
-24,
142 -0x1.20d7b6p
-4, 0x1.2083e2p
-12, 0x3.9a7aap
-8 }, /* 40 */
143 { 0x1.06531p
+7, 0x1.06532cp
+7, 0x1.065348p
+7, -0x1.691ecp
-24,
144 0x1.1d5ccap
-4, -0x1.166726p
-12, -0x1.e4af48p
-8 }, /* 41 */
145 { 0x1.0c9b9ap
+7, 0x1.0c9ba8p
+7, 0x1.0c9bbep
+7, 0x9.b406dp
-28,
146 -0x1.1a015p
-4, 0x1.038f9cp
-12, -0x4.021058p
-4 }, /* 42 */
147 { 0x1.12e412p
+7, 0x1.12e424p
+7, 0x1.12e436p
+7, -0xf.bfd8fp
-28,
148 0x1.16c37ap
-4, -0x1.039edep
-12, 0x1.f0033p
-4 }, /* 43 */
149 { 0x1.192c92p
+7, 0x1.192cap
+7, 0x1.192cb6p
+7, 0x2.6d50c8p
-24,
150 -0x1.13a19ep
-4, 0xf.9df8ap
-16, 0x4.ecd978p
-8 }, /* 44 */
151 { 0x1.1f7512p
+7, 0x1.1f751cp
+7, 0x1.1f753ap
+7, -0x4.d475c8p
-24,
152 0x1.109a32p
-4, -0x1.04fb3ap
-12, -0xd.c271p
-12 }, /* 45 */
153 { 0x1.25bd8ep
+7, 0x1.25bd98p
+7, 0x1.25bdap
+7, 0x8.1982p
-24,
154 -0x1.0dabc8p
-4, 0xe.88eabp
-16, -0x4.ed75dp
-4 }, /* 46 */
155 { 0x1.2c060cp
+7, 0x1.2c0616p
+7, 0x1.2c0644p
+7, 0x4.864518p
-24,
156 0x1.0ad51p
-4, -0xe.27196p
-16, 0xb.97a3ep
-8 }, /* 47 */
157 { 0x1.324e86p
+7, 0x1.324e92p
+7, 0x1.324e9ep
+7, 0x6.8917a8p
-28,
158 -0x1.0814d4p
-4, 0xd.4fe7ep
-16, -0x6.8d8d6p
-4 }, /* 48 */
159 { 0x1.389702p
+7, 0x1.38970ep
+7, 0x1.389728p
+7, -0x5.fa18fp
-24,
160 0x1.0569fp
-4, -0xd.5b0d4p
-16, 0x1.50353ap
-4 }, /* 49 */
161 { 0x1.3edf84p
+7, 0x1.3edf8cp
+7, 0x1.3edfaap
+7, -0x4.0e5c98p
-24,
162 -0x1.02d354p
-4, 0xb.7b255p
-16, 0x7.8a916p
-4 }, /* 50 */
163 { 0x1.4527fp
+7, 0x1.452808p
+7, 0x1.452812p
+7, -0x2.c3ddbp
-24,
164 0x1.005004p
-4, -0xd.7729cp
-16, -0x3.bcc354p
-8 }, /* 51 */
165 { 0x1.4b7076p
+7, 0x1.4b7086p
+7, 0x1.4b70a4p
+7, -0x5.d052p
-24,
166 -0xf.ddf16p
-8, 0xc.318c1p
-16, 0x5.7947p
-8 }, /* 52 */
167 { 0x1.51b8f4p
+7, 0x1.51b902p
+7, 0x1.51b90ep
+7, -0x2.0b97dcp
-24,
168 0xf.b7fafp
-8, -0xc.1429dp
-16, -0x3.43c36p
-4 }, /* 53 */
169 { 0x1.580168p
+7, 0x1.58018p
+7, 0x1.580188p
+7, -0x5.4aab5p
-24,
170 -0xf.930fep
-8, 0xa.ecc24p
-16, 0x9.c62cdp
-12 }, /* 54 */
171 { 0x1.5e49eap
+7, 0x1.5e49fcp
+7, 0x1.5e4a12p
+7, -0x3.6dadd8p
-24,
172 0xf.6f245p
-8, -0xb.6816cp
-16, 0xa.d731ap
-8 }, /* 55 */
173 { 0x1.649272p
+7, 0x1.64927ap
+7, 0x1.64929p
+7, -0x2.d7e038p
-24,
174 -0xf.4c2cep
-8, 0xb.118bep
-16, 0xb.69a4ep
-8 }, /* 56 */
175 { 0x1.6adae6p
+7, 0x1.6adaf6p
+7, 0x1.6adb04p
+7, -0x6.977a1p
-24,
176 0xf.2a1fp
-8, -0xa.a8911p
-16, -0x4.bf6d2p
-8 }, /* 57 */
177 { 0x1.712366p
+7, 0x1.712374p
+7, 0x1.71238ep
+7, 0x1.3cc95ep
-24,
178 -0xf.08f0ap
-8, 0x9.f0858p
-16, 0x1.77f7f4p
-4 }, /* 58 */
179 { 0x1.776beap
+7, 0x1.776bf2p
+7, 0x1.776bfap
+7, 0x3.a4921p
-24,
180 0xe.e8986p
-8, -0xa.39dfp
-16, -0x6.7ba3dp
-4 }, /* 59 */
181 { 0x1.7db464p
+7, 0x1.7db46ep
+7, 0x1.7db476p
+7, 0x6.b45a7p
-24,
182 -0xe.c90d8p
-8, 0xa.e586fp
-16, -0x1.d66becp
-4 }, /* 60 */
183 { 0x1.83fce2p
+7, 0x1.83fcecp
+7, 0x1.83fd0ep
+7, -0x2.8f34a4p
-24,
184 0xe.aa478p
-8, -0x9.810bp
-16, -0x3.a5f3fcp
-8 }, /* 61 */
185 { 0x1.8a455cp
+7, 0x1.8a456ap
+7, 0x1.8a4588p
+7, -0x1.325968p
-24,
186 -0xe.8c3eap
-8, 0x9.0a765p
-16, 0x1.29a54ap
-4 }, /* 62 */
187 { 0x1.908dd8p
+7, 0x1.908de8p
+7, 0x1.908df4p
+7, 0x4.96b808p
-24,
188 0xe.6eeb5p
-8, -0x9.0251bp
-16, 0x1.41a488p
-4 }, /* 63 */
191 /* Formula page 5 of https://www.cl.cam.ac.uk/~jrh13/papers/bessel.pdf:
192 j0f(x) ~ sqrt(2/(pi*x))*beta0(x)*cos(x-pi/4-alpha0(x))
193 where beta0(x) = 1 - 1/(16*x^2) + 53/(512*x^4)
194 and alpha0(x) = 1/(8*x) - 25/(384*x^3). */
198 /* The following code fails to give an error <= 9 ulps in only two cases,
199 for which we tabulate the result. */
200 if (x
== 0x1.4665d2p
+24f
)
201 return 0xa.50206p
-52f
;
202 if (x
== 0x1.a9afdep
+7f
)
203 return 0xf.47039p
-28f
;
204 double y
= 1.0 / (double) x
;
206 double beta0
= 1.0f
+ y2
* (-0x1p
-4f
+ 0x1.a8p
-4 * y2
);
207 double alpha0
= y
* (0x2p
-4 - 0x1.0aaaaap
-4 * y2
);
210 h
= reduce_aux (x
, &n
, alpha0
);
211 /* Now x - pi/4 - alpha0 = h + n*pi/2 mod (2*pi). */
212 float xr
= (float) h
;
214 float cst
= 0xc.c422ap
-4f
; /* sqrt(2/pi) rounded to nearest */
215 float t
= cst
/ sqrtf (x
) * (float) beta0
;
217 return t
* __cosf (xr
);
218 else if (n
== 2) /* cos(x+pi) = -cos(x) */
219 return -t
* __cosf (xr
);
220 else if (n
== 1) /* cos(x+pi/2) = -sin(x) */
221 return -t
* __sinf (xr
);
222 else /* cos(x+3pi/2) = sin(x) */
223 return t
* __sinf (xr
);
226 /* Special code for x near a root of j0.
227 z is the value computed by the generic code.
228 For small x, we use a polynomial approximating j0 around its root.
229 For large x, we use an asymptotic formula (j0f_asympt). */
231 j0f_near_root (float x
, float z
)
236 index_f
= roundf ((x
- FIRST_ZERO_J0
) / M_PIf
);
237 /* j0f_asympt fails to give an error <= 9 ulps for x=0x1.324e92p+7
238 (index 48) thus we can't reduce SMALL_SIZE below 49. */
239 if (index_f
>= SMALL_SIZE
)
240 return j0f_asympt (x
);
241 index
= (int) index_f
;
242 const float *p
= Pj
[index
];
245 /* If not in the interval [x0,x1] around xmid, we return the value z. */
246 if (! (x0
<= x
&& x
<= x1
))
250 return p
[3] + y
* (p
[4] + y
* (p
[5] + y
* p
[6]));
254 __ieee754_j0f(float x
)
256 float z
, s
,c
,ss
,cc
,r
,u
,v
;
259 GET_FLOAT_WORD(hx
,x
);
261 if(ix
>=0x7f800000) return one
/(x
*x
);
263 if(ix
>= 0x40000000) { /* |x| >= 2.0 */
264 SET_RESTORE_ROUNDF (FE_TONEAREST
);
265 __sincosf (x
, &s
, &c
);
268 if (ix
>= 0x7f000000)
269 /* x >= 2^127: use asymptotic expansion. */
270 return j0f_asympt (x
);
271 /* Now we are sure that x+x cannot overflow. */
273 if ((s
*c
)<zero
) cc
= z
/ss
;
276 * j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x)
277 * y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)
279 if (ix
<= 0x5c000000)
281 u
= pzerof(x
); v
= qzerof(x
);
284 z
= (invsqrtpi
* cc
) / sqrtf(x
);
285 /* The following threshold is optimal: for x=0x1.3b58dep+1
286 and rounding upwards, |cc|=0x1.579b26p-4 and z is 10 ulps
287 far from the correctly rounded value. */
288 float threshold
= 0x1.579b26p
-4f
;
289 if (fabsf (cc
) > threshold
)
292 return j0f_near_root (x
, z
);
294 if(ix
<0x39000000) { /* |x| < 2**-13 */
295 math_force_eval(huge
+x
); /* raise inexact if x != 0 */
296 if(ix
<0x32000000) return one
; /* |x|<2**-27 */
297 else return one
- (float)0.25*x
*x
;
300 r
= z
*(R02
+z
*(R03
+z
*(R04
+z
*R05
)));
301 s
= one
+z
*(S01
+z
*(S02
+z
*(S03
+z
*S04
)));
302 if(ix
< 0x3F800000) { /* |x| < 1.00 */
303 return one
+ z
*((float)-0.25+(r
/s
));
306 return((one
+u
)*(one
-u
)+z
*(r
/s
));
309 libm_alias_finite (__ieee754_j0f
, __j0f
)
312 u00
= -7.3804296553e-02, /* 0xbd9726b5 */
313 u01
= 1.7666645348e-01, /* 0x3e34e80d */
314 u02
= -1.3818567619e-02, /* 0xbc626746 */
315 u03
= 3.4745343146e-04, /* 0x39b62a69 */
316 u04
= -3.8140706238e-06, /* 0xb67ff53c */
317 u05
= 1.9559013964e-08, /* 0x32a802ba */
318 u06
= -3.9820518410e-11, /* 0xae2f21eb */
319 v01
= 1.2730483897e-02, /* 0x3c509385 */
320 v02
= 7.6006865129e-05, /* 0x389f65e0 */
321 v03
= 2.5915085189e-07, /* 0x348b216c */
322 v04
= 4.4111031494e-10; /* 0x2ff280c2 */
324 /* This is the nearest approximation of the first zero of y0. */
325 #define FIRST_ZERO_Y0 0xe.4c166p-4f
327 /* The following table contains successive zeros of y0 and degree-3
328 polynomial approximations of y0 around these zeros: Py[0] for the first
329 zero (0.89358), Py[1] for the second one (3.957678), and so on.
331 {x0, xmid, x1, p0, p1, p2, p3}
332 where [x0,x1] is the interval around the zero, xmid is the binary32 number
333 closest to the zero, and p0+p1*x+p2*x^2+p3*x^3 is the approximation
334 polynomial. Each polynomial was generated using Sollya on the interval
335 [x0,x1] around the corresponding zero where the error exceeds 9 ulps
336 for the alternate code. Degree 3 is enough, except for index 0 where we
337 use degree 5, and the coefficients of degree 4 and 5 are hard-coded in
340 static const float Py
[SMALL_SIZE
][7] = {
341 { 0x1.a681dap
-1, 0x1.c982ecp
-1, 0x1.ef6bcap
-1, 0x3.274468p
-28,
342 0xe.121b8p
-4, -0x7.df8b3p
-4, 0x3.877be4p
-4
343 /*, -0x3.a46c9p-4, 0x3.735478p-4*/ }, /* 0 */
344 { 0x1.f957c6p
+1, 0x1.fa9534p
+1, 0x1.fd11b2p
+1, 0xa.f1f83p
-28,
345 -0x6.70d098p
-4, 0xd.04d48p
-8, 0xe.f61a9p
-8 }, /* 1 */
346 { 0x1.c51832p
+2, 0x1.c581dcp
+2, 0x1.c65164p
+2, -0x5.e2a51p
-28,
347 0x4.cd3328p
-4, -0x5.6bbe08p
-8, -0xc.46d8p
-8 }, /* 2 */
348 { 0x1.46fd84p
+3, 0x1.471d74p
+3, 0x1.475bfcp
+3, -0x1.4b0aeep
-24,
349 -0x3.fec6b8p
-4, 0x3.2068a4p
-8, 0xa.76e2dp
-8 }, /* 3 */
350 { 0x1.ab7afap
+3, 0x1.ab8e1cp
+3, 0x1.abb294p
+3, -0x8.179d7p
-28,
351 0x3.7e6544p
-4, -0x2.1799fp
-8, -0x9.0e1c4p
-8 }, /* 4 */
352 { 0x1.07f9aap
+4, 0x1.0803c8p
+4, 0x1.08170cp
+4, -0x2.5b8078p
-24,
353 -0x3.24b868p
-4, 0x1.8631ecp
-8, 0x8.3cb46p
-8 }, /* 5 */
354 { 0x1.3a38eap
+4, 0x1.3a42cep
+4, 0x1.3a4d8ap
+4, 0x1.cd304ap
-28,
355 0x2.e189ecp
-4, -0x1.2c6954p
-8, -0x7.8178ep
-8 }, /* 6 */
356 { 0x1.6c7d42p
+4, 0x1.6c833p
+4, 0x1.6c99fp
+4, -0x6.c63f1p
-28,
357 -0x2.acc9a8p
-4, 0xf.09e31p
-12, 0x7.0b5ab8p
-8 }, /* 7 */
358 { 0x1.9ebec4p
+4, 0x1.9ec47p
+4, 0x1.9ed016p
+4, 0x1.e53838p
-24,
359 0x2.81f2p
-4, -0xc.5ff51p
-12, -0x7.05ep
-8 }, /* 8 */
360 { 0x1.d1008ep
+4, 0x1.d10644p
+4, 0x1.d11262p
+4, 0x1.636feep
-24,
361 -0x2.5e40dcp
-4, 0xa.6f81dp
-12, 0x5.ff6p
-8 }, /* 9 */
362 { 0x1.01a27cp
+5, 0x1.01a442p
+5, 0x1.01a924p
+5, -0x4.04e1bp
-28,
363 0x2.3febd8p
-4, -0x8.f11e2p
-12, -0x6.0111ap
-8 }, /* 10 */
364 { 0x1.1ac3bcp
+5, 0x1.1ac588p
+5, 0x1.1ac912p
+5, 0x3.6063d8p
-24,
365 -0x2.25baacp
-4, 0x7.c93cdp
-12, 0x4.e7577p
-8 }, /* 11 */
366 { 0x1.33e508p
+5, 0x1.33e6ecp
+5, 0x1.33ea1ap
+5, -0x3.f39ebcp
-24,
367 0x2.0ed04cp
-4, -0x6.d9434p
-12, -0x4.fc0b7p
-8 }, /* 12 */
368 { 0x1.4d0666p
+5, 0x1.4d0868p
+5, 0x1.4d0c14p
+5, -0x4.ea23p
-28,
369 -0x1.fa8b4p
-4, 0x6.1470e8p
-12, 0x5.97f71p
-8 }, /* 13 */
370 { 0x1.6628b8p
+5, 0x1.6629f4p
+5, 0x1.662e0ep
+5, -0x3.5df0c8p
-24,
371 0x1.e8727ep
-4, -0x5.76a038p
-12, -0x4.ee37c8p
-8 }, /* 14 */
372 { 0x1.7f4a7cp
+5, 0x1.7f4b9p
+5, 0x1.7f4daap
+5, 0x1.1ef09ep
-24,
373 -0x1.d8293ap
-4, 0x4.ed8a28p
-12, 0x4.d43708p
-8 }, /* 15 */
374 { 0x1.986c5cp
+5, 0x1.986d38p
+5, 0x1.986f6p
+5, 0x1.b70cecp
-24,
375 0x1.c967p
-4, -0x4.7a70b8p
-12, -0x5.6840e8p
-8 }, /* 16 */
376 { 0x1.b18dcap
+5, 0x1.b18ee8p
+5, 0x1.b19122p
+5, 0x1.abaadcp
-24,
377 -0x1.bbf246p
-4, 0x4.1a35bp
-12, 0x3.c2d46p
-8 }, /* 17 */
378 { 0x1.caaf86p
+5, 0x1.cab0a2p
+5, 0x1.cab2fep
+5, 0x1.63989ep
-24,
379 0x1.af9cb4p
-4, -0x3.c2f2dcp
-12, -0x4.cf8108p
-8 }, /* 18 */
380 { 0x1.e3d146p
+5, 0x1.e3d262p
+5, 0x1.e3d492p
+5, -0x1.68a8ecp
-24,
381 -0x1.a4407ep
-4, 0x3.7733ecp
-12, 0x5.97916p
-8 }, /* 19 */
382 { 0x1.fcf316p
+5, 0x1.fcf428p
+5, 0x1.fcf59ap
+5, 0x1.e1bb5p
-24,
383 0x1.99be74p
-4, -0x3.37210cp
-12, -0x5.d19bf8p
-8 }, /* 20 */
384 { 0x1.0b0a7cp
+6, 0x1.0b0afap
+6, 0x1.0b0b9cp
+6, -0x5.5bbcfp
-24,
385 -0x1.8ffc9ap
-4, 0x2.ffe638p
-12, 0x2.ed28e8p
-8 }, /* 21 */
386 { 0x1.179b66p
+6, 0x1.179bep
+6, 0x1.179d0ap
+6, -0x4.9e34a8p
-24,
387 0x1.86e51cp
-4, -0x2.cc7a68p
-12, -0x3.3642c4p
-8 }, /* 22 */
388 { 0x1.242c5cp
+6, 0x1.242ccap
+6, 0x1.242d68p
+6, 0x1.966706p
-24,
389 -0x1.7e657p
-4, 0x2.9aed4cp
-12, 0x7.b87a58p
-8 }, /* 23 */
390 { 0x1.30bd62p
+6, 0x1.30bdb6p
+6, 0x1.30beb2p
+6, 0x3.4b3b68p
-24,
391 0x1.766dc2p
-4, -0x2.72651cp
-12, -0x3.e347f8p
-8 }, /* 24 */
392 { 0x1.3d4e56p
+6, 0x1.3d4ea2p
+6, 0x1.3d4f2ep
+6, 0x6.a99008p
-28,
393 -0x1.6ef07ep
-4, 0x2.53aec4p
-12, 0x2.9e3d88p
-12 }, /* 25 */
394 { 0x1.49df38p
+6, 0x1.49df9p
+6, 0x1.49e042p
+6, -0x7.a9fa6p
-32,
395 0x1.67e1dap
-4, -0x2.324d7p
-12, -0xc.0e669p
-12 }, /* 26 */
396 { 0x1.56702ep
+6, 0x1.56708p
+6, 0x1.567116p
+6, -0x5.026808p
-24,
397 -0x1.613798p
-4, 0x2.114594p
-12, 0x1.a22402p
-8 }, /* 27 */
398 { 0x1.630126p
+6, 0x1.63017p
+6, 0x1.630226p
+6, 0x4.46aa2p
-24,
399 0x1.5ae8c2p
-4, -0x1.f4aaa4p
-12, -0x3.58593cp
-8 }, /* 28 */
400 { 0x1.6f9234p
+6, 0x1.6f926p
+6, 0x1.6f92b2p
+6, 0x1.5cfccp
-24,
401 -0x1.54ed76p
-4, 0x1.dd540ap
-12, -0xb.e9429p
-12 }, /* 29 */
402 { 0x1.7c22fep
+6, 0x1.7c2352p
+6, 0x1.7c23c2p
+6, -0xb.4dc4cp
-28,
403 0x1.4f3ebcp
-4, -0x1.c463fp
-12, -0x1.e94c54p
-8 }, /* 30 */
404 { 0x1.88b412p
+6, 0x1.88b444p
+6, 0x1.88b50ap
+6, 0x3.f5343p
-24,
405 -0x1.49d668p
-4, 0x1.a53f24p
-12, 0x5.128198p
-8 }, /* 31 */
406 { 0x1.9544dcp
+6, 0x1.954538p
+6, 0x1.95459p
+6, -0x6.e6f32p
-28,
407 0x1.44aefap
-4, -0x1.9a6ef8p
-12, -0x6.c639cp
-8 }, /* 32 */
408 { 0x1.a1d5fap
+6, 0x1.a1d62cp
+6, 0x1.a1d674p
+6, 0x1.f359c2p
-28,
409 -0x1.3fc386p
-4, 0x1.887ebep
-12, 0x1.6c813cp
-8 }, /* 33 */
410 { 0x1.ae66cp
+6, 0x1.ae672p
+6, 0x1.ae6788p
+6, -0x2.9de748p
-24,
411 0x1.3b0fa4p
-4, -0x1.777f26p
-12, 0x1.c128ccp
-8 }, /* 34 */
412 { 0x1.baf7c2p
+6, 0x1.baf816p
+6, 0x1.baf86cp
+6, -0x2.24ccc8p
-24,
413 -0x1.368f5cp
-4, 0x1.62bd9ep
-12, 0xa.df002p
-8 }, /* 35 */
414 { 0x1.c788dap
+6, 0x1.c7890cp
+6, 0x1.c7896cp
+6, 0x4.7dcea8p
-24,
415 0x1.323f16p
-4, -0x1.61abf4p
-12, 0xa.ad73ep
-8 }, /* 36 */
416 { 0x1.d419ccp
+6, 0x1.d41a02p
+6, 0x1.d41a68p
+6, -0x4.b538p
-24,
417 -0x1.2e1b98p
-4, 0x1.4a4d64p
-12, 0x3.a47674p
-8 }, /* 37 */
418 { 0x1.e0aacep
+6, 0x1.e0aaf8p
+6, 0x1.e0ab5ep
+6, 0x3.09dc4cp
-24,
419 0x1.2a21ecp
-4, -0x1.3fa20cp
-12, 0x2.216e8cp
-8 }, /* 38 */
420 { 0x1.ed3bb8p
+6, 0x1.ed3beep
+6, 0x1.ed3c56p
+6, 0x4.d5a58p
-28,
421 -0x1.264f66p
-4, 0x1.32c4cep
-12, 0x1.53cbb4p
-8 }, /* 39 */
422 { 0x1.f9ccaep
+6, 0x1.f9cce6p
+6, 0x1.f9cd52p
+6, 0x3.f4c44cp
-24,
423 0x1.22a192p
-4, -0x1.1f8514p
-12, -0xc.0de32p
-8 }, /* 40 */
424 { 0x1.032ed6p
+7, 0x1.032eeep
+7, 0x1.032f0cp
+7, 0x2.4beae8p
-24,
425 -0x1.1f1634p
-4, 0x1.171664p
-12, 0x1.72a654p
-4 }, /* 41 */
426 { 0x1.097756p
+7, 0x1.09776ap
+7, 0x1.09779cp
+7, -0xd.a581ep
-28,
427 0x1.1bab3cp
-4, -0xf.9f507p
-16, -0xc.ba2d4p
-8 }, /* 42 */
428 { 0x1.0fbfdp
+7, 0x1.0fbfe6p
+7, 0x1.0fbff6p
+7, 0xa.7c0bdp
-28,
429 -0x1.185eccp
-4, 0x1.01d7dep
-12, -0x1.a2186ep
-4 }, /* 43 */
430 { 0x1.160856p
+7, 0x1.160862p
+7, 0x1.16087ap
+7, -0x1.9452ecp
-24,
431 0x1.152f26p
-4, -0x1.07b4aap
-12, 0x1.6bbd7ep
-4 }, /* 44 */
432 { 0x1.1c50dp
+7, 0x1.1c50dep
+7, 0x1.1c5118p
+7, 0x3.83b7b8p
-24,
433 -0x1.121ab2p
-4, 0x1.0e938cp
-12, -0x5.1a6dfp
-8 }, /* 45 */
434 { 0x1.22995p
+7, 0x1.22995ap
+7, 0x1.229976p
+7, -0x6.5ca3a8p
-24,
435 0x1.0f1ff2p
-4, -0xe.f198p
-16, -0x3.8e98b8p
-8 }, /* 46 */
436 { 0x1.28e1ccp
+7, 0x1.28e1d8p
+7, 0x1.28e1f4p
+7, -0x6.bb61ap
-24,
437 -0x1.0c3d8ap
-4, 0xf.a14b9p
-16, 0x9.81e82p
-4 }, /* 47 */
438 { 0x1.2f2a48p
+7, 0x1.2f2a54p
+7, 0x1.2f2a74p
+7, 0x2.2438p
-24,
439 0x1.097236p
-4, -0xd.fed5ep
-16, -0x3.19eb5cp
-8 }, /* 48 */
440 { 0x1.3572b8p
+7, 0x1.3572dp
+7, 0x1.3572ecp
+7, 0x3.1e0054p
-24,
441 -0x1.06bcc8p
-4, 0xd.d2596p
-16, -0x1.67e00ap
-4 }, /* 49 */
442 { 0x1.3bbb3ep
+7, 0x1.3bbb4ep
+7, 0x1.3bbb6ap
+7, 0x7.46c908p
-24,
443 0x1.041c28p
-4, -0xd.04045p
-16, -0x8.fb297p
-8 }, /* 50 */
444 { 0x1.4203aep
+7, 0x1.4203cap
+7, 0x1.4203e6p
+7, -0xb.4f158p
-28,
445 -0x1.018f52p
-4, 0xc.ccf6fp
-16, 0x1.4d5dp
-4 }, /* 51 */
446 { 0x1.484c38p
+7, 0x1.484c46p
+7, 0x1.484c56p
+7, -0x6.5a89c8p
-24,
447 0xf.f155p
-8, -0xc.5d21dp
-16, -0xd.aca34p
-8 }, /* 52 */
448 { 0x1.4e94b8p
+7, 0x1.4e94c4p
+7, 0x1.4e94d4p
+7, -0x1.ef16c8p
-24,
449 -0xf.cad3fp
-8, 0xb.d75f8p
-16, 0x1.f36732p
-4 }, /* 53 */
450 { 0x1.54dd36p
+7, 0x1.54dd4p
+7, 0x1.54dd52p
+7, -0x6.1e7b68p
-24,
451 0xf.a564cp
-8, -0xb.ec1cfp
-16, 0xe.e7421p
-8 }, /* 54 */
452 { 0x1.5b25aep
+7, 0x1.5b25bep
+7, 0x1.5b25d4p
+7, -0xf.8c858p
-28,
453 -0xf.80faep
-8, 0xb.8b6c5p
-16, -0x5.835ed8p
-8 }, /* 55 */
454 { 0x1.616e34p
+7, 0x1.616e3cp
+7, 0x1.616e4ep
+7, 0x7.75d858p
-24,
455 0xf.5d8abp
-8, -0xb.b3779p
-16, 0x2.40b948p
-4 }, /* 56 */
456 { 0x1.67b6bp
+7, 0x1.67b6b8p
+7, 0x1.67b6dp
+7, 0x1.d78632p
-24,
457 -0xf.3b096p
-8, 0xa.daf89p
-16, 0x1.aa8548p
-8 }, /* 57 */
458 { 0x1.6dff28p
+7, 0x1.6dff36p
+7, 0x1.6dff54p
+7, 0x3.b24794p
-24,
459 0xf.196c7p
-8, -0xb.1afe1p
-16, -0x1.77538cp
-8 }, /* 58 */
460 { 0x1.7447a2p
+7, 0x1.7447b2p
+7, 0x1.7447cap
+7, 0x6.39cbc8p
-24,
461 -0xe.f8aa5p
-8, 0xa.50daap
-16, 0x1.9592c2p
-8 }, /* 59 */
462 { 0x1.7a902p
+7, 0x1.7a903p
+7, 0x1.7a903ep
+7, -0x1.820e3ap
-24,
463 0xe.d8b9dp
-8, -0xa.998cp
-16, -0x2.c35d78p
-4 }, /* 60 */
464 { 0x1.80d89ep
+7, 0x1.80d8aep
+7, 0x1.80d8bep
+7, -0x2.c7e038p
-24,
465 -0xe.b9925p
-8, 0x9.ce06p
-16, -0x2.2b3054p
-4 }, /* 61 */
466 { 0x1.87211cp
+7, 0x1.87212cp
+7, 0x1.872144p
+7, 0x6.ab31c8p
-24,
467 0xe.9b2bep
-8, -0x9.4de7p
-16, -0x1.32cb5ep
-4 }, /* 62 */
468 { 0x1.8d699ap
+7, 0x1.8d69a8p
+7, 0x1.8d69bp
+7, 0x4.4ef25p
-24,
469 -0xe.7d7ecp
-8, 0x9.a0f1ep
-16, 0x1.6ac076p
-4 }, /* 63 */
472 /* Formula page 5 of https://www.cl.cam.ac.uk/~jrh13/papers/bessel.pdf:
473 y0(x) ~ sqrt(2/(pi*x))*beta0(x)*sin(x-pi/4-alpha0(x))
474 where beta0(x) = 1 - 1/(16*x^2) + 53/(512*x^4)
475 and alpha0(x) = 1/(8*x) - 25/(384*x^3). */
479 /* The following code fails to give an error <= 9 ulps in only two cases,
480 for which we tabulate the correctly-rounded result. */
481 if (x
== 0x1.bfad96p
+7f
)
482 return -0x7.f32bdp
-32f
;
483 if (x
== 0x1.2e2a42p
+17f
)
484 return 0x1.a48974p
-40f
;
485 double y
= 1.0 / (double) x
;
487 double beta0
= 1.0f
+ y2
* (-0x1p
-4f
+ 0x1.a8p
-4 * y2
);
488 double alpha0
= y
* (0x2p
-4 - 0x1.0aaaaap
-4 * y2
);
491 h
= reduce_aux (x
, &n
, alpha0
);
492 /* Now x - pi/4 - alpha0 = h + n*pi/2 mod (2*pi). */
493 float xr
= (float) h
;
495 float cst
= 0xc.c422ap
-4; /* sqrt(2/pi) rounded to nearest */
496 float t
= cst
/ sqrtf (x
) * (float) beta0
;
498 return t
* __sinf (xr
);
499 else if (n
== 2) /* sin(x+pi) = -sin(x) */
500 return -t
* __sinf (xr
);
501 else if (n
== 1) /* sin(x+pi/2) = cos(x) */
502 return t
* __cosf (xr
);
503 else /* sin(x+3pi/2) = -cos(x) */
504 return -t
* __cosf (xr
);
507 /* Special code for x near a root of y0.
508 z is the value computed by the generic code.
509 For small x, use a polynomial approximating y0 around its root.
510 For large x, use an asymptotic formula (y0f_asympt). */
512 y0f_near_root (float x
, float z
)
517 index_f
= roundf ((x
- FIRST_ZERO_Y0
) / M_PIf
);
518 if (index_f
>= SMALL_SIZE
)
519 return y0f_asympt (x
);
520 index
= (int) index_f
;
521 const float *p
= Py
[index
];
524 /* If not in the interval [x0,x1] around xmid, return the value z. */
525 if (! (x0
<= x
&& x
<= x1
))
529 /* For degree 0 use a degree-5 polynomial, where the coefficients of
530 degree 4 and 5 are hard-coded. */
531 float p6
= (index
> 0) ? p
[6]
532 : p
[6] + y
* (-0x3.a46c9p
-4 + y
* 0x3.735478p
-4);
533 float res
= p
[3] + y
* (p
[4] + y
* (p
[5] + y
* p6
));
538 __ieee754_y0f(float x
)
540 float z
, s
,c
,ss
,cc
,u
,v
;
543 GET_FLOAT_WORD(hx
,x
);
545 /* Y0(NaN) is NaN, y0(-inf) is Nan, y0(inf) is 0, y0(0) is -inf. */
546 if(ix
>=0x7f800000) return one
/(x
+x
*x
);
547 if(ix
==0) return -1/zero
; /* -inf and divide by zero exception. */
548 if(hx
<0) return zero
/(zero
*x
);
549 if(ix
>= 0x40000000 || (0x3f5340ed <= ix
&& ix
<= 0x3f77b5e5)) {
551 0x1.a681dap-1 <= |x| <= 0x1.ef6bcap-1 (around 1st zero) */
552 /* y0(x) = sqrt(2/(pi*x))*(p0(x)*sin(x0)+q0(x)*cos(x0))
555 * cos(x0) = cos(x)cos(pi/4)+sin(x)sin(pi/4)
556 * = 1/sqrt(2) * (sin(x) + cos(x))
557 * sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
558 * = 1/sqrt(2) * (sin(x) - cos(x))
559 * To avoid cancellation, use
560 * sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
561 * to compute the worse one.
563 SET_RESTORE_ROUNDF (FE_TONEAREST
);
564 __sincosf (x
, &s
, &c
);
568 * j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x)
569 * y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x)
571 if (ix
>= 0x7f000000)
572 /* x >= 2^127: use asymptotic expansion. */
573 return y0f_asympt (x
);
574 /* Now we are sure that x+x cannot overflow. */
576 if ((s
*c
)<zero
) cc
= z
/ss
;
578 if (ix
<= 0x5c000000)
580 u
= pzerof(x
); v
= qzerof(x
);
583 z
= (invsqrtpi
*ss
)/sqrtf(x
);
584 /* The following threshold is optimal (determined on
585 aarch64-linux-gnu). */
586 float threshold
= 0x1.be585ap
-4;
587 if (fabsf (ss
) > threshold
)
590 return y0f_near_root (x
, z
);
592 if(ix
<=0x39800000) { /* x < 2**-13 */
593 return(u00
+ tpi
*__ieee754_logf(x
));
596 u
= u00
+z
*(u01
+z
*(u02
+z
*(u03
+z
*(u04
+z
*(u05
+z
*u06
)))));
597 v
= one
+z
*(v01
+z
*(v02
+z
*(v03
+z
*v04
)));
598 return(u
/v
+ tpi
*(__ieee754_j0f(x
)*__ieee754_logf(x
)));
600 libm_alias_finite (__ieee754_y0f
, __y0f
)
602 /* The asymptotic expansion of pzero is
603 * 1 - 9/128 s^2 + 11025/98304 s^4 - ..., where s = 1/x.
604 * For x >= 2, We approximate pzero by
605 * pzero(x) = 1 + (R/S)
606 * where R = pR0 + pR1*s^2 + pR2*s^4 + ... + pR5*s^10
607 * S = 1 + pS0*s^2 + ... + pS4*s^10
609 * | pzero(x)-1-R/S | <= 2 ** ( -60.26)
611 static const float pR8
[6] = { /* for x in [inf, 8]=1/[0,0.125] */
612 0.0000000000e+00, /* 0x00000000 */
613 -7.0312500000e-02, /* 0xbd900000 */
614 -8.0816707611e+00, /* 0xc1014e86 */
615 -2.5706311035e+02, /* 0xc3808814 */
616 -2.4852163086e+03, /* 0xc51b5376 */
617 -5.2530439453e+03, /* 0xc5a4285a */
619 static const float pS8
[5] = {
620 1.1653436279e+02, /* 0x42e91198 */
621 3.8337448730e+03, /* 0x456f9beb */
622 4.0597855469e+04, /* 0x471e95db */
623 1.1675296875e+05, /* 0x47e4087c */
624 4.7627726562e+04, /* 0x473a0bba */
626 static const float pR5
[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
627 -1.1412546255e-11, /* 0xad48c58a */
628 -7.0312492549e-02, /* 0xbd8fffff */
629 -4.1596107483e+00, /* 0xc0851b88 */
630 -6.7674766541e+01, /* 0xc287597b */
631 -3.3123129272e+02, /* 0xc3a59d9b */
632 -3.4643338013e+02, /* 0xc3ad3779 */
634 static const float pS5
[5] = {
635 6.0753936768e+01, /* 0x42730408 */
636 1.0512523193e+03, /* 0x44836813 */
637 5.9789707031e+03, /* 0x45bad7c4 */
638 9.6254453125e+03, /* 0x461665c8 */
639 2.4060581055e+03, /* 0x451660ee */
642 static const float pR3
[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
643 -2.5470459075e-09, /* 0xb12f081b */
644 -7.0311963558e-02, /* 0xbd8fffb8 */
645 -2.4090321064e+00, /* 0xc01a2d95 */
646 -2.1965976715e+01, /* 0xc1afba52 */
647 -5.8079170227e+01, /* 0xc2685112 */
648 -3.1447946548e+01, /* 0xc1fb9565 */
650 static const float pS3
[5] = {
651 3.5856033325e+01, /* 0x420f6c94 */
652 3.6151397705e+02, /* 0x43b4c1ca */
653 1.1936077881e+03, /* 0x44953373 */
654 1.1279968262e+03, /* 0x448cffe6 */
655 1.7358093262e+02, /* 0x432d94b8 */
658 static const float pR2
[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
659 -8.8753431271e-08, /* 0xb3be98b7 */
660 -7.0303097367e-02, /* 0xbd8ffb12 */
661 -1.4507384300e+00, /* 0xbfb9b1cc */
662 -7.6356959343e+00, /* 0xc0f4579f */
663 -1.1193166733e+01, /* 0xc1331736 */
664 -3.2336456776e+00, /* 0xc04ef40d */
666 static const float pS2
[5] = {
667 2.2220300674e+01, /* 0x41b1c32d */
668 1.3620678711e+02, /* 0x430834f0 */
669 2.7047027588e+02, /* 0x43873c32 */
670 1.5387539673e+02, /* 0x4319e01a */
671 1.4657617569e+01, /* 0x416a859a */
680 GET_FLOAT_WORD(ix
,x
);
682 /* ix >= 0x40000000 for all calls to this function. */
683 if(ix
>=0x41000000) {p
= pR8
; q
= pS8
;}
684 else if(ix
>=0x40f71c58){p
= pR5
; q
= pS5
;}
685 else if(ix
>=0x4036db68){p
= pR3
; q
= pS3
;}
686 else {p
= pR2
; q
= pS2
;}
688 r
= p
[0]+z
*(p
[1]+z
*(p
[2]+z
*(p
[3]+z
*(p
[4]+z
*p
[5]))));
689 s
= one
+z
*(q
[0]+z
*(q
[1]+z
*(q
[2]+z
*(q
[3]+z
*q
[4]))));
694 /* For x >= 8, the asymptotic expansion of qzero is
695 * -1/8 s + 75/1024 s^3 - ..., where s = 1/x.
696 * We approximate pzero by
697 * qzero(x) = s*(-1.25 + (R/S))
698 * where R = qR0 + qR1*s^2 + qR2*s^4 + ... + qR5*s^10
699 * S = 1 + qS0*s^2 + ... + qS5*s^12
701 * | qzero(x)/s +1.25-R/S | <= 2 ** ( -61.22)
703 static const float qR8
[6] = { /* for x in [inf, 8]=1/[0,0.125] */
704 0.0000000000e+00, /* 0x00000000 */
705 7.3242187500e-02, /* 0x3d960000 */
706 1.1768206596e+01, /* 0x413c4a93 */
707 5.5767340088e+02, /* 0x440b6b19 */
708 8.8591972656e+03, /* 0x460a6cca */
709 3.7014625000e+04, /* 0x471096a0 */
711 static const float qS8
[6] = {
712 1.6377603149e+02, /* 0x4323c6aa */
713 8.0983447266e+03, /* 0x45fd12c2 */
714 1.4253829688e+05, /* 0x480b3293 */
715 8.0330925000e+05, /* 0x49441ed4 */
716 8.4050156250e+05, /* 0x494d3359 */
717 -3.4389928125e+05, /* 0xc8a7eb69 */
720 static const float qR5
[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */
721 1.8408595828e-11, /* 0x2da1ec79 */
722 7.3242180049e-02, /* 0x3d95ffff */
723 5.8356351852e+00, /* 0x40babd86 */
724 1.3511157227e+02, /* 0x43071c90 */
725 1.0272437744e+03, /* 0x448067cd */
726 1.9899779053e+03, /* 0x44f8bf4b */
728 static const float qS5
[6] = {
729 8.2776611328e+01, /* 0x42a58da0 */
730 2.0778142090e+03, /* 0x4501dd07 */
731 1.8847289062e+04, /* 0x46933e94 */
732 5.6751113281e+04, /* 0x475daf1d */
733 3.5976753906e+04, /* 0x470c88c1 */
734 -5.3543427734e+03, /* 0xc5a752be */
737 static const float qR3
[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */
738 4.3774099900e-09, /* 0x3196681b */
739 7.3241114616e-02, /* 0x3d95ff70 */
740 3.3442313671e+00, /* 0x405607e3 */
741 4.2621845245e+01, /* 0x422a7cc5 */
742 1.7080809021e+02, /* 0x432acedf */
743 1.6673394775e+02, /* 0x4326bbe4 */
745 static const float qS3
[6] = {
746 4.8758872986e+01, /* 0x42430916 */
747 7.0968920898e+02, /* 0x44316c1c */
748 3.7041481934e+03, /* 0x4567825f */
749 6.4604252930e+03, /* 0x45c9e367 */
750 2.5163337402e+03, /* 0x451d4557 */
751 -1.4924745178e+02, /* 0xc3153f59 */
754 static const float qR2
[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */
755 1.5044444979e-07, /* 0x342189db */
756 7.3223426938e-02, /* 0x3d95f62a */
757 1.9981917143e+00, /* 0x3fffc4bf */
758 1.4495602608e+01, /* 0x4167edfd */
759 3.1666231155e+01, /* 0x41fd5471 */
760 1.6252708435e+01, /* 0x4182058c */
762 static const float qS2
[6] = {
763 3.0365585327e+01, /* 0x41f2ecb8 */
764 2.6934811401e+02, /* 0x4386ac8f */
765 8.4478375244e+02, /* 0x44533229 */
766 8.8293585205e+02, /* 0x445cbbe5 */
767 2.1266638184e+02, /* 0x4354aa98 */
768 -5.3109550476e+00, /* 0xc0a9f358 */
777 GET_FLOAT_WORD(ix
,x
);
779 /* ix >= 0x40000000 for all calls to this function. */
780 if(ix
>=0x41000000) {p
= qR8
; q
= qS8
;}
781 else if(ix
>=0x40f71c58){p
= qR5
; q
= qS5
;}
782 else if(ix
>=0x4036db68){p
= qR3
; q
= qS3
;}
783 else {p
= qR2
; q
= qS2
;}
785 r
= p
[0]+z
*(p
[1]+z
*(p
[2]+z
*(p
[3]+z
*(p
[4]+z
*p
[5]))));
786 s
= one
+z
*(q
[0]+z
*(q
[1]+z
*(q
[2]+z
*(q
[3]+z
*(q
[4]+z
*q
[5])))));
787 return (-(float).125 + r
/s
)/x
;