source: azure_iot_hub/trunk/musl-1.1.18/src/math/coshf.c@ 388

#include "libm.h"

float coshf(float x)
{
        union {float f; uint32_t i;} u = {.f = x};
        uint32_t w;
        float t;

        /* |x| */
        u.i &= 0x7fffffff;
        x = u.f;
        w = u.i;

        /* |x| < log(2) */
        if (w < 0x3f317217) {
                if (w < 0x3f800000 - (12<<23)) {
                        FORCE_EVAL(x + 0x1p120f);
                        return 1;
                }
                t = expm1f(x);
                return 1 + t*t/(2*(1+t));
        }

        /* |x| < log(FLT_MAX) */
        if (w < 0x42b17217) {
                t = expf(x);
                return 0.5f*(t + 1/t);
        }

        /* |x| > log(FLT_MAX) or nan */
        t = __expo2f(x);
        return t;
}