module.exports = function cosh(arg) {
  //  discuss at: https://locutus.io/php/cosh/
  // original by: Onno Marsman (https://twitter.com/onnomarsman)
  //   example 1: cosh(-0.18127180117607017)
  //   returns 1: 1.0164747716114113

  return (Math.exp(arg) + Math.exp(-arg)) / 2
}