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/* origin: FreeBSD /usr/src/lib/msun/src/e_coshf.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"
float coshf(float x)
{
union {float f; uint32_t i;} u = {.f = x};
uint32_t ix;
float t;
/* |x| */
u.i &= 0x7fffffff;
x = u.f;
ix = u.i;
/* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
if (ix < 0x3eb17218) {
t = expm1f(x);
if (ix < 0x39800000)
return 1;
return 1 + t*t/(2*(1+t));
}
/* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */
if (ix < 0x41100000) {
t = expf(x);
return 0.5f*t + 0.5f/t;
}
/* |x| in [9, log(maxfloat)] return 0.5f*exp(|x|) */
if (ix < 0x42b17217)
return 0.5f*expf(x);
/* |x| in [log(maxfloat), overflowthresold] */
if (ix <= 0x42b2d4fc)
return __expo2f(x);
/* |x| > overflowthresold or nan */
x *= 0x1p127f;
return x;
}
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