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/* e_asinf.c -- float version of e_asin.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
//#include <sys/cdefs.h>
//__FBSDID("$FreeBSD$");
#include <cmath>
#include "math_private.h"
static const float
one = 1.0000000000e+00, /* 0x3F800000 */
huge = 1.000e+30,
/* coefficient for R(x^2) */
pS0 = 1.6666586697e-01,
pS1 = -4.2743422091e-02,
pS2 = -8.6563630030e-03,
qS1 = -7.0662963390e-01;
static const double
pio2 = 1.570796326794896558e+00;
float
__ieee754_asinf(float x)
{
double s;
float t,w,p,q;
int32_t hx,ix;
GET_FLOAT_WORD(hx,x);
ix = hx&0x7fffffff;
if(ix>=0x3f800000) { /* |x| >= 1 */
if(ix==0x3f800000) /* |x| == 1 */
return x*pio2; /* asin(+-1) = +-pi/2 with inexact */
return (x-x)/(x-x); /* asin(|x|>1) is NaN */
} else if (ix<0x3f000000) { /* |x|<0.5 */
if(ix<0x39800000) { /* |x| < 2**-12 */
if(huge+x>one) return x;/* return x with inexact if x!=0*/
}
t = x*x;
p = t*(pS0+t*(pS1+t*pS2));
q = one+t*qS1;
w = p/q;
return x+x*w;
}
/* 1> |x|>= 0.5 */
w = one-fabsf(x);
t = w*(float)0.5;
p = t*(pS0+t*(pS1+t*pS2));
q = one+t*qS1;
s = std::sqrt(t);
w = p/q;
t = pio2-2.0*(s+s*w);
if(hx>0) return t; else return -t;
}
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