+++ /dev/null
-/* @(#)s_atan.c 5.1 93/09/24 */\r
-/*\r
- * ====================================================\r
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.\r
- *\r
- * Developed at SunPro, a Sun Microsystems, Inc. business.\r
- * Permission to use, copy, modify, and distribute this\r
- * software is freely granted, provided that this notice\r
- * is preserved.\r
- * ====================================================\r
- */\r
-#include <LibConfig.h>\r
-#include <sys/EfiCdefs.h>\r
-#if defined(LIBM_SCCS) && !defined(lint)\r
-__RCSID("$NetBSD: s_atan.c,v 1.11 2002/05/26 22:01:54 wiz Exp $");\r
-#endif\r
-\r
-/* atan(x)\r
- * Method\r
- * 1. Reduce x to positive by atan(x) = -atan(-x).\r
- * 2. According to the integer k=4t+0.25 chopped, t=x, the argument\r
- * is further reduced to one of the following intervals and the\r
- * arctangent of t is evaluated by the corresponding formula:\r
- *\r
- * [0,7/16] atan(x) = t-t^3*(a1+t^2*(a2+...(a10+t^2*a11)...)\r
- * [7/16,11/16] atan(x) = atan(1/2) + atan( (t-0.5)/(1+t/2) )\r
- * [11/16.19/16] atan(x) = atan( 1 ) + atan( (t-1)/(1+t) )\r
- * [19/16,39/16] atan(x) = atan(3/2) + atan( (t-1.5)/(1+1.5t) )\r
- * [39/16,INF] atan(x) = atan(INF) + atan( -1/t )\r
- *\r
- * Constants:\r
- * The hexadecimal values are the intended ones for the following\r
- * constants. The decimal values may be used, provided that the\r
- * compiler will convert from decimal to binary accurately enough\r
- * to produce the hexadecimal values shown.\r
- */\r
-\r
-#include "math.h"\r
-#include "math_private.h"\r
-\r
-static const double atanhi[] = {\r
- 4.63647609000806093515e-01, /* atan(0.5)hi 0x3FDDAC67, 0x0561BB4F */\r
- 7.85398163397448278999e-01, /* atan(1.0)hi 0x3FE921FB, 0x54442D18 */\r
- 9.82793723247329054082e-01, /* atan(1.5)hi 0x3FEF730B, 0xD281F69B */\r
- 1.57079632679489655800e+00, /* atan(inf)hi 0x3FF921FB, 0x54442D18 */\r
-};\r
-\r
-static const double atanlo[] = {\r
- 2.26987774529616870924e-17, /* atan(0.5)lo 0x3C7A2B7F, 0x222F65E2 */\r
- 3.06161699786838301793e-17, /* atan(1.0)lo 0x3C81A626, 0x33145C07 */\r
- 1.39033110312309984516e-17, /* atan(1.5)lo 0x3C700788, 0x7AF0CBBD */\r
- 6.12323399573676603587e-17, /* atan(inf)lo 0x3C91A626, 0x33145C07 */\r
-};\r
-\r
-static const double aT[] = {\r
- 3.33333333333329318027e-01, /* 0x3FD55555, 0x5555550D */\r
- -1.99999999998764832476e-01, /* 0xBFC99999, 0x9998EBC4 */\r
- 1.42857142725034663711e-01, /* 0x3FC24924, 0x920083FF */\r
- -1.11111104054623557880e-01, /* 0xBFBC71C6, 0xFE231671 */\r
- 9.09088713343650656196e-02, /* 0x3FB745CD, 0xC54C206E */\r
- -7.69187620504482999495e-02, /* 0xBFB3B0F2, 0xAF749A6D */\r
- 6.66107313738753120669e-02, /* 0x3FB10D66, 0xA0D03D51 */\r
- -5.83357013379057348645e-02, /* 0xBFADDE2D, 0x52DEFD9A */\r
- 4.97687799461593236017e-02, /* 0x3FA97B4B, 0x24760DEB */\r
- -3.65315727442169155270e-02, /* 0xBFA2B444, 0x2C6A6C2F */\r
- 1.62858201153657823623e-02, /* 0x3F90AD3A, 0xE322DA11 */\r
-};\r
-\r
- static const double\r
-one = 1.0,\r
-huge = 1.0e300;\r
-\r
-double\r
-atan(double x)\r
-{\r
- double w,s1,s2,z;\r
- int32_t ix,hx,id;\r
-\r
- GET_HIGH_WORD(hx,x);\r
- ix = hx&0x7fffffff;\r
- if(ix>=0x44100000) { /* if |x| >= 2^66 */\r
- u_int32_t low;\r
- GET_LOW_WORD(low,x);\r
- if(ix>0x7ff00000||\r
- (ix==0x7ff00000&&(low!=0)))\r
- return x+x; /* NaN */\r
- if(hx>0) return atanhi[3]+atanlo[3];\r
- else return -atanhi[3]-atanlo[3];\r
- } if (ix < 0x3fdc0000) { /* |x| < 0.4375 */\r
- if (ix < 0x3e200000) { /* |x| < 2^-29 */\r
- if(huge+x>one) return x; /* raise inexact */\r
- }\r
- id = -1;\r
- } else {\r
- x = fabs(x);\r
- if (ix < 0x3ff30000) { /* |x| < 1.1875 */\r
- if (ix < 0x3fe60000) { /* 7/16 <=|x|<11/16 */\r
- id = 0; x = (2.0*x-one)/(2.0+x);\r
- } else { /* 11/16<=|x|< 19/16 */\r
- id = 1; x = (x-one)/(x+one);\r
- }\r
- } else {\r
- if (ix < 0x40038000) { /* |x| < 2.4375 */\r
- id = 2; x = (x-1.5)/(one+1.5*x);\r
- } else { /* 2.4375 <= |x| < 2^66 */\r
- id = 3; x = -1.0/x;\r
- }\r
- }}\r
- /* end of argument reduction */\r
- z = x*x;\r
- w = z*z;\r
- /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */\r
- s1 = z*(aT[0]+w*(aT[2]+w*(aT[4]+w*(aT[6]+w*(aT[8]+w*aT[10])))));\r
- s2 = w*(aT[1]+w*(aT[3]+w*(aT[5]+w*(aT[7]+w*aT[9]))));\r
- if (id<0) return x - x*(s1+s2);\r
- else {\r
- z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x);\r
- return (hx<0)? -z:z;\r
- }\r
-}\r
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