/* e_acosf.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 <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include "math.h" #include "math_private.h" static const float one = 1.0000000000e+00, /* 0x3F800000 */ pi = 3.1415925026e+00, /* 0x40490fda */ pio2_hi = 1.5707962513e+00; /* 0x3fc90fda */ static volatile float pio2_lo = 7.5497894159e-08; /* 0x33a22168 */ static const float pS0 = 1.6666586697e-01, pS1 = -4.2743422091e-02, pS2 = -8.6563630030e-03, qS1 = -7.0662963390e-01; float __ieee754_acosf(float x) { 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(ix==0x3f800000) { /* |x| == 1 */ if(hx>0) return 0.0; /* acos(1) = 0 */ else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */ } return (x-x)/(x-x); /* acos(|x|>1) is NaN */ } if(ix<0x3f000000) { /* |x| < 0.5 */ if(ix<=0x32800000) return pio2_hi+pio2_lo;/*if|x|<2**-26*/ z = x*x; p = z*(pS0+z*(pS1+z*pS2)); q = one+z*qS1; 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)); q = one+z*qS1; s = 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 = 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)); q = one+z*qS1; r = p/q; w = r*s+c; return (float)2.0*(df+w); } } |