67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
/* e_asinf.c -- float version of e_asin.c.
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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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 SunPro, 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_asinf.c,v 1.13 2008/08/08 00:21:27 das Exp $");
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#include <openlibm_math.h>
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#include "math_private.h"
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static const float
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one = 1.0000000000e+00, /* 0x3F800000 */
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huge = 1.000e+30,
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/* coefficient for R(x^2) */
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pS0 = 1.6666586697e-01,
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pS1 = -4.2743422091e-02,
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pS2 = -8.6563630030e-03,
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qS1 = -7.0662963390e-01;
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static const double
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pio2 = 1.570796326794896558e+00;
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OLM_DLLEXPORT float
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__ieee754_asinf(float x)
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{
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double s;
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float t,w,p,q;
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int32_t hx,ix;
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GET_FLOAT_WORD(hx,x);
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ix = hx&0x7fffffff;
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if(ix>=0x3f800000) { /* |x| >= 1 */
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if(ix==0x3f800000) /* |x| == 1 */
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return x*pio2; /* asin(+-1) = +-pi/2 with inexact */
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return (x-x)/(x-x); /* asin(|x|>1) is NaN */
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} else if (ix<0x3f000000) { /* |x|<0.5 */
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if(ix<0x39800000) { /* |x| < 2**-12 */
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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 = t*(pS0+t*(pS1+t*pS2));
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q = one+t*qS1;
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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-fabsf(x);
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t = w*(float)0.5;
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p = t*(pS0+t*(pS1+t*pS2));
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q = one+t*qS1;
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s = sqrt(t);
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w = p/q;
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t = pio2-2.0*(s+s*w);
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if(hx>0) return t; else return -t;
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}
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