text: "use strict";
  
  var log = Math.log;
  
  module.exports = function (value) {
  	if (isNaN(value)) return NaN;
  	value = Number(value);
  	if (value < -1) return NaN;
  	if (value > 1) return NaN;
  	if (value === -1) return -Infinity;
  	if (value === 1) return Infinity;
  	if (value === 0) return value;
  	return 0.5 * log((1 + value) / (1 - value));
  };
  