third_party/ulib/musl/src/math/coshf.c

#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;
}