From 00d483697a6e395ef6776320cd1e52a04f4367be Mon Sep 17 00:00:00 2001
From: Joseph Redmon <pjreddie@gmail.com>
Date: Wed, 30 Apr 2014 23:17:40 +0000
Subject: [PATCH] Small updates

---
 src/activations.c |   34 +++++++++++++++++++++++++++++-----
 1 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/activations.c b/src/activations.c
index c81d6aa..24868a3 100644
--- a/src/activations.c
+++ b/src/activations.c
@@ -34,21 +34,37 @@
     return RELU;
 }
 
+float linear_activate(float x){return x;}
+float sigmoid_activate(float x){return 1./(1. + exp(-x));}
+float relu_activate(float x){return x*(x>0);}
+float ramp_activate(float x){return x*(x>0)+.1*x;}
+float tanh_activate(float x){return (exp(2*x)-1)/(exp(2*x)+1);}
+
 float activate(float x, ACTIVATION a){
     switch(a){
         case LINEAR:
-            return x;
+            return linear_activate(x);
         case SIGMOID:
-            return 1./(1.+exp(-x));
+            return sigmoid_activate(x);
         case RELU:
-            return x*(x>0);
+            return relu_activate(x);
         case RAMP:
-            return x*(x>0) + .1*x;
+            return ramp_activate(x);
         case TANH:
-            return (exp(2*x)-1)/(exp(2*x)+1);
+            return tanh_activate(x);
     }
     return 0;
 }
+
+void activate_array(float *x, const int n, const ACTIVATION a)
+{
+    int i;
+    for(i = 0; i < n; ++i){
+        x[i] = activate(x[i], a);
+    }
+}
+
+
 float gradient(float x, ACTIVATION a){
     switch(a){
         case LINEAR:
@@ -65,3 +81,11 @@
     return 0;
 }
 
+void gradient_array(const float *x, const int n, const ACTIVATION a, float *delta)
+{
+    int i;
+    for(i = 0; i < n; ++i){
+        delta[i] *= gradient(x[i], a);
+    }
+} 
+

--
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