1 /* e_acosf.c -- float version of e_acos.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
13 * ====================================================
15 * $FreeBSD: head/lib/msun/src/e_acosf.c 181257 2008-08-03 17:39:54Z das $
19 #include "math_private.h"
22 one = 1.0000000000e+00, /* 0x3F800000 */
23 pi = 3.1415925026e+00, /* 0x40490fda */
24 pio2_hi = 1.5707962513e+00; /* 0x3fc90fda */
26 pio2_lo = 7.5497894159e-08; /* 0x33a22168 */
28 pS0 = 1.6666586697e-01,
29 pS1 = -4.2743422091e-02,
30 pS2 = -8.6563630030e-03,
31 qS1 = -7.0662963390e-01;
34 __ieee754_acosf(float x)
36 float z,p,q,r,w,s,c,df;
40 if(ix>=0x3f800000) { /* |x| >= 1 */
41 if(ix==0x3f800000) { /* |x| == 1 */
42 if(hx>0) return 0.0; /* acos(1) = 0 */
43 else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */
45 return (x-x)/(x-x); /* acos(|x|>1) is NaN */
47 if(ix<0x3f000000) { /* |x| < 0.5 */
48 if(ix<=0x32800000) return pio2_hi+pio2_lo;/*if|x|<2**-26*/
50 p = z*(pS0+z*(pS1+z*pS2));
53 return pio2_hi - (x - (pio2_lo-x*r));
54 } else if (hx<0) { /* x < -0.5 */
55 z = (one+x)*(float)0.5;
56 p = z*(pS0+z*(pS1+z*pS2));
61 return pi - (float)2.0*(s+w);
62 } else { /* x > 0.5 */
64 z = (one-x)*(float)0.5;
67 GET_FLOAT_WORD(idf,df);
68 SET_FLOAT_WORD(df,idf&0xfffff000);
70 p = z*(pS0+z*(pS1+z*pS2));
74 return (float)2.0*(df+w);