mirror of https://github.com/lukechilds/node.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
15 lines
289 B
15 lines
289 B
10 years ago
|
'use strict';
|
||
|
|
|
||
|
|
var log = Math.log;
|
||
|
|
|
||
|
|
module.exports = function (x) {
|
||
|
|
if (isNaN(x)) return NaN;
|
||
|
|
x = Number(x);
|
||
|
|
if (x < -1) return NaN;
|
||
|
|
if (x > 1) return NaN;
|
||
|
|
if (x === -1) return -Infinity;
|
||
|
|
if (x === 1) return Infinity;
|
||
|
|
if (x === 0) return x;
|
||
|
|
return 0.5 * log((1 + x) / (1 - x));
|
||
|
|
};
|