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 * ====================================================
16 #include <sys/cdefs.h>
18 #include "math_private.h"
21 one = 1.0000000000e+00, /* 0x3F800000 */
22 pi = 3.1415925026e+00, /* 0x40490fda */
23 pio2_hi = 1.5707962513e+00; /* 0x3fc90fda */
25 pio2_lo = 7.5497894159e-08; /* 0x33a22168 */
27 pS0 = 1.6666586697e-01,
28 pS1 = -4.2743422091e-02,
29 pS2 = -8.6563630030e-03,
30 qS1 = -7.0662963390e-01;
35 float z,p,q,r,w,s,c,df;
39 if(ix>=0x3f800000) { /* |x| >= 1 */
40 if(ix==0x3f800000) { /* |x| == 1 */
41 if(hx>0) return 0.0; /* acos(1) = 0 */
42 else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */
44 return (x-x)/(x-x); /* acos(|x|>1) is NaN */
46 if(ix<0x3f000000) { /* |x| < 0.5 */
47 if(ix<=0x32800000) return pio2_hi+pio2_lo;/*if|x|<2**-26*/
49 p = z*(pS0+z*(pS1+z*pS2));
52 return pio2_hi - (x - (pio2_lo-x*r));
53 } else if (hx<0) { /* x < -0.5 */
54 z = (one+x)*(float)0.5;
55 p = z*(pS0+z*(pS1+z*pS2));
60 return pi - (float)2.0*(s+w);
61 } else { /* x > 0.5 */
63 z = (one-x)*(float)0.5;
66 GET_FLOAT_WORD(idf,df);
67 SET_FLOAT_WORD(df,idf&0xfffff000);
69 p = z*(pS0+z*(pS1+z*pS2));
73 return (float)2.0*(df+w);