From b715671988a4f3e476586df52fa3bf052cce7f80 Mon Sep 17 00:00:00 2001
From: Joseph Redmon <pjreddie@gmail.com>
Date: Thu, 05 Dec 2013 21:17:16 +0000
Subject: [PATCH] Works well on MNIST
---
src/activations.c | 39 ++++++++-------------------------------
1 files changed, 8 insertions(+), 31 deletions(-)
diff --git a/src/activations.c b/src/activations.c
index a255f0f..b8bb79d 100644
--- a/src/activations.c
+++ b/src/activations.c
@@ -8,15 +8,16 @@
{
if (strcmp(s, "sigmoid")==0) return SIGMOID;
if (strcmp(s, "relu")==0) return RELU;
- if (strcmp(s, "identity")==0) return IDENTITY;
+ if (strcmp(s, "linear")==0) return LINEAR;
if (strcmp(s, "ramp")==0) return RAMP;
+ if (strcmp(s, "tanh")==0) return TANH;
fprintf(stderr, "Couldn't find activation function %s, going with ReLU\n", s);
return RELU;
}
double activate(double x, ACTIVATION a){
switch(a){
- case IDENTITY:
+ case LINEAR:
return x;
case SIGMOID:
return 1./(1.+exp(-x));
@@ -24,12 +25,14 @@
return x*(x>0);
case RAMP:
return x*(x>0) + .1*x;
+ case TANH:
+ return (exp(2*x)-1)/(exp(2*x)+1);
}
return 0;
}
double gradient(double x, ACTIVATION a){
switch(a){
- case IDENTITY:
+ case LINEAR:
return 1;
case SIGMOID:
return (1.-x)*x;
@@ -37,35 +40,9 @@
return (x>0);
case RAMP:
return (x>0) + .1;
+ case TANH:
+ return 1-x*x;
}
return 0;
}
-double identity_activation(double x)
-{
- return x;
-}
-double identity_gradient(double x)
-{
- return 1;
-}
-
-double relu_activation(double x)
-{
- return x*(x>0);
-}
-double relu_gradient(double x)
-{
- return (x>0);
-}
-
-double sigmoid_activation(double x)
-{
- return 1./(1.+exp(-x));
-}
-
-double sigmoid_gradient(double x)
-{
- return x*(1.-x);
-}
-
--
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