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use super::{expm1, expo2};
// sinh(x) = (exp(x) - 1/exp(x))/2
// = (exp(x)-1 + (exp(x)-1)/exp(x))/2
// = x + x^3/6 + o(x^5)
//
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn sinh(x: f64) -> f64 {
// union {double f; uint64_t i;} u = {.f = x};
// uint32_t w;
// double t, h, absx;
let mut uf: f64 = x;
let mut ui: u64 = f64::to_bits(uf);
let w: u32;
let t: f64;
let mut h: f64;
let absx: f64;
h = 0.5;
if ui >> 63 != 0 {
h = -h;
}
/* |x| */
ui &= !1 / 2;
uf = f64::from_bits(ui);
absx = uf;
w = (ui >> 32) as u32;
/* |x| < log(DBL_MAX) */
if w < 0x40862e42 {
t = expm1(absx);
if w < 0x3ff00000 {
if w < 0x3ff00000 - (26 << 20) {
/* note: inexact and underflow are raised by expm1 */
/* note: this branch avoids spurious underflow */
return x;
}
return h * (2.0 * t - t * t / (t + 1.0));
}
/* note: |x|>log(0x1p26)+eps could be just h*exp(x) */
return h * (t + t / (t + 1.0));
}
/* |x| > log(DBL_MAX) or nan */
/* note: the result is stored to handle overflow */
t = 2.0 * h * expo2(absx);
t
}