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/* origin: FreeBSD /usr/src/lib/msun/src/e_asinf.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 "libm.h"
static const double
pio2 = 1.570796326794896558e+00;
static const float
/* coefficients for R(x^2) */
pS0 = 1.6666586697e-01,
pS1 = -4.2743422091e-02,
pS2 = -8.6563630030e-03,
qS1 = -7.0662963390e-01;
static float R(float z)
{
float_t p, q;
p = z*(pS0+z*(pS1+z*pS2));
q = 1.0f+z*qS1;
return p/q;
}
float asinf(float x)
{
double s;
float z;
uint32_t hx,ix;
GET_FLOAT_WORD(hx, x);
ix = hx & 0x7fffffff;
if (ix >= 0x3f800000) { /* |x| >= 1 */
if (ix == 0x3f800000) /* |x| == 1 */
return x*pio2 + 0x1p-120f; /* asin(+-1) = +-pi/2 with inexact */
return 0/(x-x); /* asin(|x|>1) is NaN */
}
if (ix < 0x3f000000) { /* |x| < 0.5 */
/* if 0x1p-126 <= |x| < 0x1p-12, avoid raising underflow */
if (ix < 0x39800000 && ix >= 0x00800000)
return x;
return x + x*R(x*x);
}
/* 1 > |x| >= 0.5 */
z = (1 - fabsf(x))*0.5f;
s = sqrt(z);
x = pio2 - 2*(s+s*R(z));
if (hx >> 31)
return -x;
return x;
}
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