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use super::exp;
use super::expm1;
use super::k_expo2;
/// Hyperbolic cosine (f64)
///
/// Computes the hyperbolic cosine of the argument x.
/// Is defined as `(exp(x) + exp(-x))/2`
/// Angles are specified in radians.
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn cosh(mut x: f64) -> f64 {
/* |x| */
let mut ix = x.to_bits();
ix &= 0x7fffffffffffffff;
x = f64::from_bits(ix);
let w = ix >> 32;
/* |x| < log(2) */
if w < 0x3fe62e42 {
if w < 0x3ff00000 - (26 << 20) {
let x1p120 = f64::from_bits(0x4770000000000000);
force_eval!(x + x1p120);
return 1.;
}
let t = expm1(x); // exponential minus 1
return 1. + t * t / (2. * (1. + t));
}
/* |x| < log(DBL_MAX) */
if w < 0x40862e42 {
let t = exp(x);
/* note: if x>log(0x1p26) then the 1/t is not needed */
return 0.5 * (t + 1. / t);
}
/* |x| > log(DBL_MAX) or nan */
k_expo2(x)
}