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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libm/] [math/] [ef_acos.c] - Rev 859
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/* ef_acos.c -- float version of e_acos.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 #else static float #endif one = 1.0000000000e+00, /* 0x3F800000 */ pi = 3.1415925026e+00, /* 0x40490fda */ pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */ pio2_lo = 7.5497894159e-08, /* 0x33a22168 */ pS0 = 1.6666667163e-01, /* 0x3e2aaaab */ pS1 = -3.2556581497e-01, /* 0xbea6b090 */ pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */ pS3 = -4.0055535734e-02, /* 0xbd241146 */ pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */ pS5 = 3.4793309169e-05, /* 0x3811ef08 */ qS1 = -2.4033949375e+00, /* 0xc019d139 */ qS2 = 2.0209457874e+00, /* 0x4001572d */ qS3 = -6.8828397989e-01, /* 0xbf303361 */ qS4 = 7.7038154006e-02; /* 0x3d9dc62e */ #ifdef __STDC__ float __ieee754_acosf(float x) #else float __ieee754_acosf(x) float x; #endif { float z,p,q,r,w,s,c,df; __int32_t hx,ix; GET_FLOAT_WORD(hx,x); ix = hx&0x7fffffff; if(ix==0x3f800000) { /* |x|==1 */ if(hx>0) return 0.0; /* acos(1) = 0 */ else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */ } else if(ix>0x3f800000) { /* |x| >= 1 */ return (x-x)/(x-x); /* acos(|x|>1) is NaN */ } if(ix<0x3f000000) { /* |x| < 0.5 */ if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/ z = x*x; p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); r = p/q; return pio2_hi - (x - (pio2_lo-x*r)); } else if (hx<0) { /* x < -0.5 */ z = (one+x)*(float)0.5; p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); s = __ieee754_sqrtf(z); r = p/q; w = r*s-pio2_lo; return pi - (float)2.0*(s+w); } else { /* x > 0.5 */ __int32_t idf; z = (one-x)*(float)0.5; s = __ieee754_sqrtf(z); df = s; GET_FLOAT_WORD(idf,df); SET_FLOAT_WORD(df,idf&0xfffff000); c = (z-df*df)/(s+df); p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); r = p/q; w = r*s+c; return (float)2.0*(df+w); } }
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