15 lines
337 B
JavaScript
15 lines
337 B
JavaScript
"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));
|
|
};
|