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/* origin: FreeBSD /usr/src/lib/msun/src/e_acosl.c */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* See comments in acos.c.
* Converted to long double by David Schultz <das@FreeBSD.ORG>.
*/
#include "libm.h"
#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
long double acosl(long double x)
{
return acos(x);
}
#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
#include "__invtrigl.h"
long double acosl(long double x)
{
union IEEEl2bits u;
long double z, w, s, c, df;
int16_t expsign, expt;
u.e = x;
expsign = u.xbits.expsign;
expt = expsign & 0x7fff;
/* |x| >= 1 or nan */
if (expt >= 0x3fff) {
if (expt == 0x3fff &&
((u.bits.manh & ~LDBL_NBIT) | u.bits.manl) == 0) {
if (expsign > 0)
return 0; /* acos(1) = 0 */
return 2*pio2_hi + 0x1p-120f; /* acos(-1)= pi */
}
return 0/(x-x); /* acos(|x|>1) is NaN */
}
/* |x| < 0.5 */
if (expt < 0x3fff - 1) {
if (expt < 0x3fff - 65)
return pio2_hi + 0x1p-120f; /* x < 0x1p-65: acosl(x)=pi/2 */
return pio2_hi - (x - (pio2_lo - x * __invtrigl_R(x*x)));
}
/* x < -0.5 */
if (expsign < 0) {
z = (1.0 + x) * 0.5;
s = sqrtl(z);
w = __invtrigl_R(z) * s - pio2_lo;
return 2*(pio2_hi - (s + w));
}
/* x > 0.5 */
z = (1.0 - x) * 0.5;
s = sqrtl(z);
u.e = s;
u.bits.manl = 0;
df = u.e;
c = (z - df * df) / (s + df);
w = __invtrigl_R(z) * s + c;
return 2*(df + w);
}
#endif
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