From e99043d4ac7412554fc0d3ed95e79fe6fbb62ddc Mon Sep 17 00:00:00 2001
From: Mikatech <mikael.vallenet@epitech.eu>
Date: Thu, 4 Aug 2022 23:25:04 +0200
Subject: [PATCH] feat(neural): add tanh func & derivate in neural funcs pkg

---
 neural/funcs.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/neural/funcs.go b/neural/funcs.go
index 48bf3db8..cbf5b8c6 100644
--- a/neural/funcs.go
+++ b/neural/funcs.go
@@ -12,6 +12,14 @@ var Sigmoid NeuralFunction = NeuralFunction{
 	func(v float64) float64 { return v * (1 - v) },
 }
 
+// TanhForward function does tanh(t) = \frac{1 - e^{-2t}}{1 + e^{-2t}}
+//
+// See https://en.wikipedia.org/wiki/Hyperbolic_functions
+var Tanh NeuralFunction = NeuralFunction{
+	func(v float64) float64 { return math.Tanh(v) },
+	func(v float64) float64 { return 1 - (v * v) },
+}
+
 // LinearFunction doesn't modify the value
 var Linear NeuralFunction = NeuralFunction{
 	func(v float64) float64 { return v },