+++ /dev/null
-
-/* @(#)s_atan.c 5.1 93/09/24 */
-/*
- * ====================================================
- * 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.
- * ====================================================
- *
- */
-
-/*
-FUNCTION
- <<atan>>, <<atanf>>---arc tangent
-
-INDEX
- atan
-INDEX
- atanf
-
-ANSI_SYNOPSIS
- #include <math.h>
- double atan(double <[x]>);
- float atanf(float <[x]>);
-
-TRAD_SYNOPSIS
- #include <math.h>
- double atan(<[x]>);
- double <[x]>;
-
- float atanf(<[x]>);
- float <[x]>;
-
-DESCRIPTION
-
-<<atan>> computes the inverse tangent (arc tangent) of the input value.
-
-<<atanf>> is identical to <<atan>>, save that it operates on <<floats>>.
-
-RETURNS
-@ifinfo
-<<atan>> returns a value in radians, in the range of -pi/2 to pi/2.
-@end ifinfo
-@tex
-<<atan>> returns a value in radians, in the range of $-\pi/2$ to $\pi/2$.
-@end tex
-
-PORTABILITY
-<<atan>> is ANSI C. <<atanf>> is an extension.
-
-*/
-
-/* 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 "fdlibm.h"
-
-#ifndef _DOUBLE_IS_32BITS
-
-#ifdef __STDC__
-static const double atanhi[] = {
-#else
-static double atanhi[] = {
-#endif
- 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 */
-};
-
-#ifdef __STDC__
-static const double atanlo[] = {
-#else
-static double atanlo[] = {
-#endif
- 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 */
-};
-
-#ifdef __STDC__
-static const double aT[] = {
-#else
-static double aT[] = {
-#endif
- 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 */
-};
-
-#ifdef __STDC__
- static const double
-#else
- static double
-#endif
-one = 1.0,
-huge = 1.0e300;
-
-#ifdef __STDC__
- double atan(double x)
-#else
- double atan(x)
- double x;
-#endif
-{
- 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 */
- uint32_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;
- }
-}
-
-#endif /* _DOUBLE_IS_32BITS */
projects / msp430-gcc.git / blobdiff