This repository has been archived by the owner on Feb 11, 2021. It is now read-only.
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Added atan implementation from uClibc
- Loading branch information
Showing
5 changed files
with
128 additions
and
1 deletion.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| /* | ||
| * ==================================================== | ||
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | ||
| * | ||
| * 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. | ||
| * ==================================================== | ||
| */ | ||
|
|
||
| /* atan(x) | ||
| * Method | ||
| * 1. Reduce x to positive by atan(x) = -atan(-x). | ||
| * 2. According to the integer k=4t+0.25 chopped, t=x, the argument | ||
| * is further reduced to one of the following intervals and the | ||
| * arctangent of t is evaluated by the corresponding formula: | ||
| * | ||
| * [0,7/16] atan(x) = t-t^3*(a1+t^2*(a2+...(a10+t^2*a11)...) | ||
| * [7/16,11/16] atan(x) = atan(1/2) + atan( (t-0.5)/(1+t/2) ) | ||
| * [11/16.19/16] atan(x) = atan( 1 ) + atan( (t-1)/(1+t) ) | ||
| * [19/16,39/16] atan(x) = atan(3/2) + atan( (t-1.5)/(1+1.5t) ) | ||
| * [39/16,INF] atan(x) = atan(INF) + atan( -1/t ) | ||
| * | ||
| * Constants: | ||
| * The hexadecimal values are the intended ones for the following | ||
| * constants. The decimal values may be used, provided that the | ||
| * compiler will convert from decimal to binary accurately enough | ||
| * to produce the hexadecimal values shown. | ||
| */ | ||
|
|
||
| #include "math.h" | ||
| #include "math_private.h" | ||
|
|
||
| static const double atanhi[] = { | ||
| 4.63647609000806093515e-01, /* atan(0.5)hi 0x3FDDAC67, 0x0561BB4F */ | ||
| 7.85398163397448278999e-01, /* atan(1.0)hi 0x3FE921FB, 0x54442D18 */ | ||
| 9.82793723247329054082e-01, /* atan(1.5)hi 0x3FEF730B, 0xD281F69B */ | ||
| 1.57079632679489655800e+00, /* atan(inf)hi 0x3FF921FB, 0x54442D18 */ | ||
| }; | ||
|
|
||
| static const double atanlo[] = { | ||
| 2.26987774529616870924e-17, /* atan(0.5)lo 0x3C7A2B7F, 0x222F65E2 */ | ||
| 3.06161699786838301793e-17, /* atan(1.0)lo 0x3C81A626, 0x33145C07 */ | ||
| 1.39033110312309984516e-17, /* atan(1.5)lo 0x3C700788, 0x7AF0CBBD */ | ||
| 6.12323399573676603587e-17, /* atan(inf)lo 0x3C91A626, 0x33145C07 */ | ||
| }; | ||
|
|
||
| static const double aT[] = { | ||
| 3.33333333333329318027e-01, /* 0x3FD55555, 0x5555550D */ | ||
| -1.99999999998764832476e-01, /* 0xBFC99999, 0x9998EBC4 */ | ||
| 1.42857142725034663711e-01, /* 0x3FC24924, 0x920083FF */ | ||
| -1.11111104054623557880e-01, /* 0xBFBC71C6, 0xFE231671 */ | ||
| 9.09088713343650656196e-02, /* 0x3FB745CD, 0xC54C206E */ | ||
| -7.69187620504482999495e-02, /* 0xBFB3B0F2, 0xAF749A6D */ | ||
| 6.66107313738753120669e-02, /* 0x3FB10D66, 0xA0D03D51 */ | ||
| -5.83357013379057348645e-02, /* 0xBFADDE2D, 0x52DEFD9A */ | ||
| 4.97687799461593236017e-02, /* 0x3FA97B4B, 0x24760DEB */ | ||
| -3.65315727442169155270e-02, /* 0xBFA2B444, 0x2C6A6C2F */ | ||
| 1.62858201153657823623e-02, /* 0x3F90AD3A, 0xE322DA11 */ | ||
| }; | ||
|
|
||
| static const double | ||
| one = 1.0, | ||
| huge = 1.0e300; | ||
|
|
||
| double atan(double x) | ||
| { | ||
| double w,s1,s2,z; | ||
| int32_t ix,hx,id; | ||
|
|
||
| GET_HIGH_WORD(hx,x); | ||
| ix = hx&0x7fffffff; | ||
| if(ix>=0x44100000) { /* if |x| >= 2^66 */ | ||
| u_int32_t low; | ||
| GET_LOW_WORD(low,x); | ||
| if(ix>0x7ff00000|| | ||
| (ix==0x7ff00000&&(low!=0))) | ||
| return x+x; /* NaN */ | ||
| if(hx>0) return atanhi[3]+atanlo[3]; | ||
| else return -atanhi[3]-atanlo[3]; | ||
| } if (ix < 0x3fdc0000) { /* |x| < 0.4375 */ | ||
| if (ix < 0x3e200000) { /* |x| < 2^-29 */ | ||
| if(huge+x>one) return x; /* raise inexact */ | ||
| } | ||
| id = -1; | ||
| } else { | ||
| x = fabs(x); | ||
| if (ix < 0x3ff30000) { /* |x| < 1.1875 */ | ||
| if (ix < 0x3fe60000) { /* 7/16 <=|x|<11/16 */ | ||
| id = 0; x = (2.0*x-one)/(2.0+x); | ||
| } else { /* 11/16<=|x|< 19/16 */ | ||
| id = 1; x = (x-one)/(x+one); | ||
| } | ||
| } else { | ||
| if (ix < 0x40038000) { /* |x| < 2.4375 */ | ||
| id = 2; x = (x-1.5)/(one+1.5*x); | ||
| } else { /* 2.4375 <= |x| < 2^66 */ | ||
| id = 3; x = -1.0/x; | ||
| } | ||
| }} | ||
| /* end of argument reduction */ | ||
| z = x*x; | ||
| w = z*z; | ||
| /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */ | ||
| s1 = z*(aT[0]+w*(aT[2]+w*(aT[4]+w*(aT[6]+w*(aT[8]+w*aT[10]))))); | ||
| s2 = w*(aT[1]+w*(aT[3]+w*(aT[5]+w*(aT[7]+w*aT[9])))); | ||
| if (id<0) return x - x*(s1+s2); | ||
| else { | ||
| z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x); | ||
| return (hx<0)? -z:z; | ||
| } | ||
| } | ||
| libm_hidden_def(atan) |