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>
17 //__FBSDID("$FreeBSD$");
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
);