78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
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/* @(#)e_asin.c 1.3 95/01/18 */
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/* FreeBSD: head/lib/msun/src/e_asin.c 176451 2008-02-22 02:30:36Z das */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include "cdefs-compat.h"
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//__FBSDID("$FreeBSD: src/lib/msun/src/e_asinl.c,v 1.2 2008/08/03 17:49:05 das Exp $");
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/*
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* See comments in e_asin.c.
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* Converted to long double by David Schultz <das@FreeBSD.ORG>.
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*/
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#include <float.h>
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#include <openlibm_math.h>
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#include "invtrig.h"
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#include "math_private.h"
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static const long double
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one = 1.00000000000000000000e+00,
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huge = 1.000e+300;
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OLM_DLLEXPORT long double
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asinl(long double x)
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{
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union IEEEl2bits u;
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long double t=0.0,w,p,q,c,r,s;
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int16_t expsign, expt;
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u.e = x;
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expsign = u.xbits.expsign;
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expt = expsign & 0x7fff;
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if(expt >= BIAS) { /* |x|>= 1 */
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if(expt==BIAS && ((u.bits.manh&~LDBL_NBIT)|u.bits.manl)==0)
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/* asin(1)=+-pi/2 with inexact */
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return x*pio2_hi+x*pio2_lo;
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return (x-x)/(x-x); /* asin(|x|>1) is NaN */
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} else if (expt<BIAS-1) { /* |x|<0.5 */
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if(expt<ASIN_LINEAR) { /* if |x| is small, asinl(x)=x */
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if(huge+x>one) return x;/* return x with inexact if x!=0*/
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}
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t = x*x;
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p = P(t);
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q = Q(t);
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w = p/q;
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return x+x*w;
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}
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/* 1> |x|>= 0.5 */
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w = one-fabsl(x);
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t = w*0.5;
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p = P(t);
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q = Q(t);
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s = sqrtl(t);
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if(u.bits.manh>=THRESH) { /* if |x| is close to 1 */
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w = p/q;
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t = pio2_hi-(2.0*(s+s*w)-pio2_lo);
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} else {
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u.e = s;
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u.bits.manl = 0;
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w = u.e;
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c = (t-w*w)/(s+w);
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r = p/q;
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p = 2.0*s*r-(pio2_lo-2.0*c);
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q = pio4_hi-2.0*w;
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t = pio4_hi-(p-q);
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}
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if(expsign>0) return t; else return -t;
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}
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