Subversion Repositories shark

Rev

Details | Last modification | View Log | RSS feed

Rev Author Line No. Line
2 pj 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
#ifndef lint
17
static char rcsid[] = "$\Id: e_asinf.c,v 1.3 1996/07/12 18:57:47 jkh Exp $";
18
#endif
19
 
20
#include "math.h"
21
#include "math_private.h"
22
 
23
#ifdef __STDC__
24
static const float
25
#else
26
static float
27
#endif
28
one =  1.0000000000e+00, /* 0x3F800000 */
29
huge =  1.000e+30,
30
pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
31
pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
32
pio4_hi =  7.8539818525e-01, /* 0x3f490fdb */
33
        /* coefficient for R(x^2) */
34
pS0 =  1.6666667163e-01, /* 0x3e2aaaab */
35
pS1 = -3.2556581497e-01, /* 0xbea6b090 */
36
pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
37
pS3 = -4.0055535734e-02, /* 0xbd241146 */
38
pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
39
pS5 =  3.4793309169e-05, /* 0x3811ef08 */
40
qS1 = -2.4033949375e+00, /* 0xc019d139 */
41
qS2 =  2.0209457874e+00, /* 0x4001572d */
42
qS3 = -6.8828397989e-01, /* 0xbf303361 */
43
qS4 =  7.7038154006e-02; /* 0x3d9dc62e */
44
 
45
#ifdef __STDC__
46
        float __ieee754_asinf(float x)
47
#else
48
        float __ieee754_asinf(x)
49
        float x;
50
#endif
51
{
52
        float t=0.0,w,p,q,c,r,s;
53
        int32_t hx,ix;
54
        GET_FLOAT_WORD(hx,x);
55
        ix = hx&0x7fffffff;
56
        if(ix==0x3f800000) {
57
                /* asin(1)=+-pi/2 with inexact */
58
            return x*pio2_hi+x*pio2_lo;
59
        } else if(ix> 0x3f800000) {     /* |x|>= 1 */
60
            return (x-x)/(x-x);         /* asin(|x|>1) is NaN */
61
        } else if (ix<0x3f000000) {     /* |x|<0.5 */
62
            if(ix<0x32000000) {         /* if |x| < 2**-27 */
63
                if(huge+x>one) return x;/* return x with inexact if x!=0*/
64
            } else
65
                t = x*x;
66
                p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
67
                q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
68
                w = p/q;
69
                return x+x*w;
70
        }
71
        /* 1> |x|>= 0.5 */
72
        w = one-fabsf(x);
73
        t = w*(float)0.5;
74
        p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
75
        q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
76
        s = sqrtf(t);
77
        if(ix>=0x3F79999A) {    /* if |x| > 0.975 */
78
            w = p/q;
79
            t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo);
80
        } else {
81
            int32_t iw;
82
            w  = s;
83
            GET_FLOAT_WORD(iw,w);
84
            SET_FLOAT_WORD(w,iw&0xfffff000);
85
            c  = (t-w*w)/(s+w);
86
            r  = p/q;
87
            p  = (float)2.0*s*r-(pio2_lo-(float)2.0*c);
88
            q  = pio4_hi-(float)2.0*w;
89
            t  = pio4_hi-(p-q);
90
        }
91
        if(hx>0) return t; else return -t;
92
}