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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 float
huge = 1.000e+30,
/* coefficients 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 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 > 1.0f)
return x; /* return x with inexact if x!=0 */
}
t = x*x;
p = t*(pS0+t*(pS1+t*pS2));
q = 1.0f+t*qS1;
w = p/q;
return x + x*w;
}
/* 1 > |x| >= 0.5 */
w = 1.0f - fabsf(x);
t = w*0.5f;
p = t*(pS0+t*(pS1+t*pS2));
q = 1.0f+t*qS1;
s = sqrt(t);
w = p/q;
t = pio2-2.0*(s+s*w);
if (hx > 0)
return t;
return -t;
}
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