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
19static const float
20one =  1.0000000000e+00, /* 0x3F800000 */
21huge =  1.000e+30,
22pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
23pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
24pio4_hi =  7.8539818525e-01, /* 0x3f490fdb */
25	/* coefficient for R(x^2) */
26pS0 =  1.6666667163e-01, /* 0x3e2aaaab */
27pS1 = -3.2556581497e-01, /* 0xbea6b090 */
28pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
29pS3 = -4.0055535734e-02, /* 0xbd241146 */
30pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
31pS5 =  3.4793309169e-05, /* 0x3811ef08 */
32qS1 = -2.4033949375e+00, /* 0xc019d139 */
33qS2 =  2.0209457874e+00, /* 0x4001572d */
34qS3 = -6.8828397989e-01, /* 0xbf303361 */
35qS4 =  7.7038154006e-02; /* 0x3d9dc62e */
36
37float
38asinf(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}
81DEF_STD(asinf);
82