2 /* @(#)e_asin.c 1.3 95/01/18 */
3 /* FreeBSD: head/lib/msun/src/e_asin.c 176451 2008-02-22 02:30:36Z das */
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 * Developed at SunSoft, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
12 * ====================================================
15 #include <sys/cdefs.h>
16 __FBSDID("$FreeBSD$");
19 * See comments in e_asin.c.
20 * Converted to long double by David Schultz <das@FreeBSD.ORG>.
27 #include "math_private.h"
29 static const long double
30 one = 1.00000000000000000000e+00,
37 long double t=0.0,w,p,q,c,r,s;
38 int16_t expsign, expt;
40 expsign = u.xbits.expsign;
41 expt = expsign & 0x7fff;
42 if(expt >= BIAS) { /* |x|>= 1 */
43 if(expt==BIAS && ((u.bits.manh&~LDBL_NBIT)|u.bits.manl)==0)
44 /* asin(1)=+-pi/2 with inexact */
45 return x*pio2_hi+x*pio2_lo;
46 return (x-x)/(x-x); /* asin(|x|>1) is NaN */
47 } else if (expt<BIAS-1) { /* |x|<0.5 */
48 if(expt<ASIN_LINEAR) { /* if |x| is small, asinl(x)=x */
49 if(huge+x>one) return x;/* return x with inexact if x!=0*/
63 if(u.bits.manh>=THRESH) { /* if |x| is close to 1 */
65 t = pio2_hi-(2.0*(s+s*w)-pio2_lo);
72 p = 2.0*s*r-(pio2_lo-2.0*c);
76 if(expsign>0) return t; else return -t;