From c2ae5d3f4cb5925856e9f30618d2940fef0b4cab Mon Sep 17 00:00:00 2001
From: rolux <rolux@rolux.org>
Date: Wed, 13 Jun 2012 00:04:28 +0200
Subject: [PATCH] add acosh, atanh and tanh

---
 source/Ox/js/Math.js | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/source/Ox/js/Math.js b/source/Ox/js/Math.js
index fe0a79c9..4b8f7baf 100644
--- a/source/Ox/js/Math.js
+++ b/source/Ox/js/Math.js
@@ -1,5 +1,13 @@
 'use strict';
 
+/*@
+Ox.acosh <f> Inverse hyperbolic cosine
+    Missing from `Math`.
+@*/
+Ox.acosh = function(x) {
+    return Math.log(x + Math.sqrt(x * x - 1));
+};
+
 /*@
 Ox.asinh <f> Inverse hyperbolic sine
     Missing from `Math`.
@@ -10,6 +18,14 @@ Ox.asinh = function(x) {
     return Math.log(x + Math.sqrt(x * x + 1));
 };
 
+/*@
+Ox.atanh <f> Inverse hyperbolic tangent
+    Missing from `Math`.
+@*/
+Ox.atanh = function(x) {
+    return 0.5 * Math.log((1 + x) / (1 - x));
+};
+
 /*@
 Ox.deg <f> Takes radians, returns degrees
     Missing from `Math`.
@@ -140,3 +156,11 @@ Ox.sinh <f> Hyperbolic sine
 Ox.sinh = function(x) {
     return (Math.exp(x) - Math.exp(-x)) / 2;
 };
+
+/*@
+Ox.tanh <f> Hyperbolic tangent
+    Missing from `Math`.
+@*/
+Ox.tanh = function(x) {
+    return (Math.exp(x) - Math.exp(-x)) / (Math.exp(x) + Math.exp(-x));
+};