1 /* e_asinf.c -- float version of e_asin.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5 /*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
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
12 * is preserved.
13 * ====================================================
14 */
15
16 #include "math.h"
17 #include "math_private.h"
18
19 static const float
20 one = 1.0000000000e+00, /* 0x3F800000 */
21 huge = 1.000e+30,
22 pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */
23 pio2_lo = 7.5497894159e-08, /* 0x33a22168 */
24 pio4_hi = 7.8539818525e-01, /* 0x3f490fdb */
25 /* coefficient for R(x^2) */
26 pS0 = 1.6666667163e-01, /* 0x3e2aaaab */
27 pS1 = -3.2556581497e-01, /* 0xbea6b090 */
28 pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */
29 pS3 = -4.0055535734e-02, /* 0xbd241146 */
30 pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */
31 pS5 = 3.4793309169e-05, /* 0x3811ef08 */
32 qS1 = -2.4033949375e+00, /* 0xc019d139 */
33 qS2 = 2.0209457874e+00, /* 0x4001572d */
34 qS3 = -6.8828397989e-01, /* 0xbf303361 */
35 qS4 = 7.7038154006e-02; /* 0x3d9dc62e */
36
37 float
asinf(float x)38 asinf(float x)
39 {
40 float t,w,p,q,c,r,s;
41 int32_t hx,ix;
42 GET_FLOAT_WORD(hx,x);
43 ix = hx&0x7fffffff;
44 if(ix==0x3f800000) {
45 /* asin(1)=+-pi/2 with inexact */
46 return x*pio2_hi+x*pio2_lo;
47 } else if(ix> 0x3f800000) { /* |x|>= 1 */
48 return (x-x)/(x-x); /* asin(|x|>1) is NaN */
49 } else if (ix<0x3f000000) { /* |x|<0.5 */
50 if(ix<0x32000000) { /* if |x| < 2**-27 */
51 if(huge+x>one) return x;/* return x with inexact if x!=0*/
52 }
53 t = x*x;
54 p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
55 q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
56 w = p/q;
57 return x+x*w;
58 }
59 /* 1> |x|>= 0.5 */
60 w = one-fabsf(x);
61 t = w*(float)0.5;
62 p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
63 q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
64 s = sqrtf(t);
65 if(ix>=0x3F79999A) { /* if |x| > 0.975 */
66 w = p/q;
67 t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo);
68 } else {
69 int32_t iw;
70 w = s;
71 GET_FLOAT_WORD(iw,w);
72 SET_FLOAT_WORD(w,iw&0xfffff000);
73 c = (t-w*w)/(s+w);
74 r = p/q;
75 p = (float)2.0*s*r-(pio2_lo-(float)2.0*c);
76 q = pio4_hi-(float)2.0*w;
77 t = pio4_hi-(p-q);
78 }
79 if(hx>0) return t; else return -t;
80 }
81 DEF_STD(asinf);
82