Issue with the exp layer when the base is e

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>

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;