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comparison packages/language/c/libm/current/src/float/portable-api/sf_atan.c @ 3337:77f9d3253c3e

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Add: Complex number header and library (single and double precision floating point), port from Newlib. Add: Single precision floating point library, port from Newlib. [ Bugzilla 1001539 ]
author vae
date Sun, 25 Aug 2013 14:38:57 +0000
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3336:8ecac279f33c 3337:77f9d3253c3e
1 //===========================================================================
2 //
3 // sf_atan.c
4 //
5 // Part of the standard mathematical function library
6 //
7 //===========================================================================
8 // ####ECOSGPLCOPYRIGHTBEGIN####
9 // -------------------------------------------
10 // This file is part of eCos, the Embedded Configurable Operating System.
11 // Copyright (C) 2012 Free Software Foundation, Inc.
12 //
13 // eCos is free software; you can redistribute it and/or modify it under
14 // the terms of the GNU General Public License as published by the Free
15 // Software Foundation; either version 2 or (at your option) any later
16 // version.
17 //
18 // eCos is distributed in the hope that it will be useful, but WITHOUT
19 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
20 // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
21 // for more details.
22 //
23 // You should have received a copy of the GNU General Public License
24 // along with eCos; if not, write to the Free Software Foundation, Inc.,
25 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
26 //
27 // As a special exception, if other files instantiate templates or use
28 // macros or inline functions from this file, or you compile this file
29 // and link it with other works to produce a work based on this file,
30 // this file does not by itself cause the resulting work to be covered by
31 // the GNU General Public License. However the source code for this file
32 // must still be made available in accordance with section (3) of the GNU
33 // General Public License v2.
34 //
35 // This exception does not invalidate any other reasons why a work based
36 // on this file might be covered by the GNU General Public License.
37 // -------------------------------------------
38 // ####ECOSGPLCOPYRIGHTEND####
39 //===========================================================================
40 //#####DESCRIPTIONBEGIN####
41 //
42 // Author(s):
43 // Contributors: visar, ilijak
44 // Date: 2012-03-08
45 // Purpose:
46 // Description:
47 // Usage:
48 //
49 //####DESCRIPTIONEND####
50 //
51 //===========================================================================
52
53 // CONFIGURATION
54
55 #include <pkgconf/libm.h> // Configuration header
56
57 // Include the Math library?
58 #ifdef CYGPKG_LIBM
59
60 // Derived from code with the following copyright
61
62
63 /* sf_atan.c -- float version of s_atan.c.
64 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
65 */
66
67 /*
68 * ====================================================
69 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
70 *
71 * Developed at SunPro, a Sun Microsystems, Inc. business.
72 * Permission to use, copy, modify, and distribute this
73 * software is freely granted, provided that this notice
74 * is preserved.
75 * ====================================================
76 *
77 */
78
79
80 #include "mathincl/fdlibm.h"
81
82 #ifdef __STDC__
83 static const float atanhi[] = {
84 #else
85 static float atanhi[] = {
86 #endif
87 4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */
88 7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */
89 9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */
90 1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */
91 };
92
93 #ifdef __STDC__
94 static const float atanlo[] = {
95 #else
96 static float atanlo[] = {
97 #endif
98 5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */
99 3.7748947079e-08, /* atan(1.0)lo 0x33222168 */
100 3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */
101 7.5497894159e-08, /* atan(inf)lo 0x33a22168 */
102 };
103
104 #ifdef __STDC__
105 static const float aT[] = {
106 #else
107 static float aT[] = {
108 #endif
109 3.3333334327e-01, /* 0x3eaaaaaa */
110 -2.0000000298e-01, /* 0xbe4ccccd */
111 1.4285714924e-01, /* 0x3e124925 */
112 -1.1111110449e-01, /* 0xbde38e38 */
113 9.0908870101e-02, /* 0x3dba2e6e */
114 -7.6918758452e-02, /* 0xbd9d8795 */
115 6.6610731184e-02, /* 0x3d886b35 */
116 -5.8335702866e-02, /* 0xbd6ef16b */
117 4.9768779427e-02, /* 0x3d4bda59 */
118 -3.6531571299e-02, /* 0xbd15a221 */
119 1.6285819933e-02, /* 0x3c8569d7 */
120 };
121
122 #ifdef __STDC__
123 static const float
124 #else
125 static float
126 #endif
127 one = 1.0,
128 huge = 1.0e30;
129
130 #ifdef __STDC__
131 float atanf(float x)
132 #else
133 float atanf(x)
134 float x;
135 #endif
136 {
137 float w,s1,s2,z;
138 __int32_t ix,hx,id;
139
140 hx = CYG_LIBM_WORD(x);
141 ix = hx&0x7fffffff;
142 if(ix>=0x50800000) { /* if |x| >= 2^34 */
143 if(FLT_UWORD_IS_NAN(ix))
144 return x+x; /* NaN */
145 if(hx>0) return atanhi[3]+atanlo[3];
146 else return -atanhi[3]-atanlo[3];
147 } if (ix < 0x3ee00000) { /* |x| < 0.4375 */
148 if (ix < 0x31000000) { /* |x| < 2^-29 */
149 if(huge+x>one) return x; /* raise inexact */
150 }
151 id = -1;
152 } else {
153 x = fabsf(x);
154 if (ix < 0x3f980000) { /* |x| < 1.1875 */
155 if (ix < 0x3f300000) { /* 7/16 <=|x|<11/16 */
156 id = 0; x = ((float)2.0*x-one)/((float)2.0+x);
157 } else { /* 11/16<=|x|< 19/16 */
158 id = 1; x = (x-one)/(x+one);
159 }
160 } else {
161 if (ix < 0x401c0000) { /* |x| < 2.4375 */
162 id = 2; x = (x-(float)1.5)/(one+(float)1.5*x);
163 } else { /* 2.4375 <= |x| < 2^66 */
164 id = 3; x = -(float)1.0/x;
165 }
166 }}
167 /* end of argument reduction */
168 z = x*x;
169 w = z*z;
170 /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */
171 s1 = z*(aT[0]+w*(aT[2]+w*(aT[4]+w*(aT[6]+w*(aT[8]+w*aT[10])))));
172 s2 = w*(aT[1]+w*(aT[3]+w*(aT[5]+w*(aT[7]+w*aT[9]))));
173 if (id<0) return x - x*(s1+s2);
174 else {
175 z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x);
176 return (hx<0)? -z:z;
177 }
178 }
179
180
181 #endif // ifdef CYGPKG_LIBM
182
183 // EOF sf_atan.c