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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [math/] [sf_atan.c] - Rev 214
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/* sf_atan.c -- float version of s_atan.c. * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. */ /* * ==================================================== * 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. * ==================================================== * */ #include "fdlibm.h" #ifdef __STDC__ static const float atanhi[] = { #else static float atanhi[] = { #endif 4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */ 7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */ 9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */ 1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */ }; #ifdef __STDC__ static const float atanlo[] = { #else static float atanlo[] = { #endif 5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */ 3.7748947079e-08, /* atan(1.0)lo 0x33222168 */ 3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */ 7.5497894159e-08, /* atan(inf)lo 0x33a22168 */ }; #ifdef __STDC__ static const float aT[] = { #else static float aT[] = { #endif 3.3333334327e-01, /* 0x3eaaaaaa */ -2.0000000298e-01, /* 0xbe4ccccd */ 1.4285714924e-01, /* 0x3e124925 */ -1.1111110449e-01, /* 0xbde38e38 */ 9.0908870101e-02, /* 0x3dba2e6e */ -7.6918758452e-02, /* 0xbd9d8795 */ 6.6610731184e-02, /* 0x3d886b35 */ -5.8335702866e-02, /* 0xbd6ef16b */ 4.9768779427e-02, /* 0x3d4bda59 */ -3.6531571299e-02, /* 0xbd15a221 */ 1.6285819933e-02, /* 0x3c8569d7 */ }; #ifdef __STDC__ static const float #else static float #endif one = 1.0, huge = 1.0e30; #ifdef __STDC__ float atanf(float x) #else float atanf(x) float x; #endif { float w,s1,s2,z; __int32_t ix,hx,id; GET_FLOAT_WORD(hx,x); ix = hx&0x7fffffff; if(ix>=0x50800000) { /* if |x| >= 2^34 */ if(FLT_UWORD_IS_NAN(ix)) return x+x; /* NaN */ if(hx>0) return atanhi[3]+atanlo[3]; else return -atanhi[3]-atanlo[3]; } if (ix < 0x3ee00000) { /* |x| < 0.4375 */ if (ix < 0x31000000) { /* |x| < 2^-29 */ if(huge+x>one) return x; /* raise inexact */ } id = -1; } else { x = fabsf(x); if (ix < 0x3f980000) { /* |x| < 1.1875 */ if (ix < 0x3f300000) { /* 7/16 <=|x|<11/16 */ id = 0; x = ((float)2.0*x-one)/((float)2.0+x); } else { /* 11/16<=|x|< 19/16 */ id = 1; x = (x-one)/(x+one); } } else { if (ix < 0x401c0000) { /* |x| < 2.4375 */ id = 2; x = (x-(float)1.5)/(one+(float)1.5*x); } else { /* 2.4375 <= |x| < 2^66 */ id = 3; x = -(float)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; } } #ifdef _DOUBLE_IS_32BITS #ifdef __STDC__ double atan(double x) #else double atan(x) double x; #endif { return (double) atanf((float) x); } #endif /* defined(_DOUBLE_IS_32BITS) */
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