From 3c3dc95766c8caa374c643b51bd92a27f787b8b5 Mon Sep 17 00:00:00 2001
From: emmanuel maggiori <emaggior@rachmaninov.inria.fr>
Date: Fri, 8 Apr 2016 10:25:12 +0200
Subject: [PATCH] Solving issue with exp layer with base e

---
 src/caffe/layers/exp_layer.cpp       |  3 ++-
 src/caffe/test/test_neuron_layer.cpp | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/caffe/layers/exp_layer.cpp b/src/caffe/layers/exp_layer.cpp
index 1f4a309fe25..0c1b463ae12 100644
--- a/src/caffe/layers/exp_layer.cpp
+++ b/src/caffe/layers/exp_layer.cpp
@@ -23,7 +23,8 @@ void ExpLayer<Dtype>::LayerSetUp(const vector<Blob<Dtype>*>& bottom,
   const Dtype input_scale = this->layer_param_.exp_param().scale();
   const Dtype input_shift = this->layer_param_.exp_param().shift();
   inner_scale_ = log_base * input_scale;
-  outer_scale_ = (input_shift == Dtype(0)) ? Dtype(1) : pow(base, input_shift);
+  outer_scale_ = (input_shift == Dtype(0)) ? Dtype(1) :
+     ( (base != Dtype(-1)) ? pow(base, input_shift) : exp(input_shift) );
 }
 
 template <typename Dtype>
diff --git a/src/caffe/test/test_neuron_layer.cpp b/src/caffe/test/test_neuron_layer.cpp
index dd591f7d204..342f825cec3 100644
--- a/src/caffe/test/test_neuron_layer.cpp
+++ b/src/caffe/test/test_neuron_layer.cpp
@@ -394,6 +394,26 @@ TYPED_TEST(NeuronLayerTest, TestExpGradient) {
   this->TestExpGradient(kBase, kScale, kShift);
 }
 
+TYPED_TEST(NeuronLayerTest, TestExpLayerWithShift) {
+  typedef typename TypeParam::Dtype Dtype;
+  // Test default base of "-1" -- should actually set base := e,
+  // with a non-zero shift
+  const Dtype kBase = -1;
+  const Dtype kScale = 1;
+  const Dtype kShift = 1;
+  this->TestExpForward(kBase, kScale, kShift);
+}
+
+TYPED_TEST(NeuronLayerTest, TestExpGradientWithShift) {
+  typedef typename TypeParam::Dtype Dtype;
+  // Test default base of "-1" -- should actually set base := e,
+  // with a non-zero shift
+  const Dtype kBase = -1;
+  const Dtype kScale = 1;
+  const Dtype kShift = 1;
+  this->TestExpGradient(kBase, kScale, kShift);
+}
+
 TYPED_TEST(NeuronLayerTest, TestExpLayerBase2) {
   typedef typename TypeParam::Dtype Dtype;
   const Dtype kBase = 2;