Tied weights with transpose flag for InnerProduct layer

include/caffe/layers/inner_product_layer.hpp

@@ -44,6 +44,7 @@ class InnerProductLayer : public Layer<Dtype> {
   int N_;
   bool bias_term_;
   Blob<Dtype> bias_multiplier_;
+  bool transpose_;  ///< if true, assume transposed weights
 };
 
 }  // namespace caffe

src/caffe/layers/inner_product_layer.cpp

@@ -11,6 +11,7 @@ void InnerProductLayer<Dtype>::LayerSetUp(const vector<Blob<Dtype>*>& bottom,
       const vector<Blob<Dtype>*>& top) {
   const int num_output = this->layer_param_.inner_product_param().num_output();
   bias_term_ = this->layer_param_.inner_product_param().bias_term();
+  transpose_ = this->layer_param_.inner_product_param().transpose();
   N_ = num_output;
   const int axis = bottom[0]->CanonicalAxisIndex(
       this->layer_param_.inner_product_param().axis());
@@ -27,10 +28,15 @@ void InnerProductLayer<Dtype>::LayerSetUp(const vector<Blob<Dtype>*>& bottom,
     } else {
       this->blobs_.resize(1);
     }
-    // Intialize the weight
+    // Initialize the weights
     vector<int> weight_shape(2);
-    weight_shape[0] = N_;
-    weight_shape[1] = K_;
+    if (transpose_) {
+      weight_shape[0] = K_;
+      weight_shape[1] = N_;
+    } else {
+      weight_shape[0] = N_;
+      weight_shape[1] = K_;
+    }
     this->blobs_[0].reset(new Blob<Dtype>(weight_shape));
     // fill the weights
     shared_ptr<Filler<Dtype> > weight_filler(GetFiller<Dtype>(
@@ -80,7 +86,8 @@ void InnerProductLayer<Dtype>::Forward_cpu(const vector<Blob<Dtype>*>& bottom,
   const Dtype* bottom_data = bottom[0]->cpu_data();
   Dtype* top_data = top[0]->mutable_cpu_data();
   const Dtype* weight = this->blobs_[0]->cpu_data();
-  caffe_cpu_gemm<Dtype>(CblasNoTrans, CblasTrans, M_, N_, K_, (Dtype)1.,
+  caffe_cpu_gemm<Dtype>(CblasNoTrans, transpose_ ? CblasNoTrans : CblasTrans,
+      M_, N_, K_, (Dtype)1.,
       bottom_data, weight, (Dtype)0., top_data);
   if (bias_term_) {
     caffe_cpu_gemm<Dtype>(CblasNoTrans, CblasNoTrans, M_, N_, 1, (Dtype)1.,
@@ -97,8 +104,17 @@ void InnerProductLayer<Dtype>::Backward_cpu(const vector<Blob<Dtype>*>& top,
     const Dtype* top_diff = top[0]->cpu_diff();
     const Dtype* bottom_data = bottom[0]->cpu_data();
     // Gradient with respect to weight
-    caffe_cpu_gemm<Dtype>(CblasTrans, CblasNoTrans, N_, K_, M_, (Dtype)1.,
-        top_diff, bottom_data, (Dtype)1., this->blobs_[0]->mutable_cpu_diff());
+    if (transpose_) {
+      caffe_cpu_gemm<Dtype>(CblasTrans, CblasNoTrans,
+          K_, N_, M_,
+          (Dtype)1., bottom_data, top_diff,
+          (Dtype)1., this->blobs_[0]->mutable_cpu_diff());
+    } else {
+      caffe_cpu_gemm<Dtype>(CblasTrans, CblasNoTrans,
+          N_, K_, M_,
+          (Dtype)1., top_diff, bottom_data,
+          (Dtype)1., this->blobs_[0]->mutable_cpu_diff());
+    }
   }
   if (bias_term_ && this->param_propagate_down_[1]) {
     const Dtype* top_diff = top[0]->cpu_diff();
@@ -110,9 +126,17 @@ void InnerProductLayer<Dtype>::Backward_cpu(const vector<Blob<Dtype>*>& top,
   if (propagate_down[0]) {
     const Dtype* top_diff = top[0]->cpu_diff();
     // Gradient with respect to bottom data
-    caffe_cpu_gemm<Dtype>(CblasNoTrans, CblasNoTrans, M_, K_, N_, (Dtype)1.,
-        top_diff, this->blobs_[0]->cpu_data(), (Dtype)0.,
-        bottom[0]->mutable_cpu_diff());
+    if (transpose_) {
+      caffe_cpu_gemm<Dtype>(CblasNoTrans, CblasTrans,
+          M_, K_, N_,
+          (Dtype)1., top_diff, this->blobs_[0]->cpu_data(),
+          (Dtype)0., bottom[0]->mutable_cpu_diff());
+    } else {
+      caffe_cpu_gemm<Dtype>(CblasNoTrans, CblasNoTrans,
+          M_, K_, N_,
+          (Dtype)1., top_diff, this->blobs_[0]->cpu_data(),
+          (Dtype)0., bottom[0]->mutable_cpu_diff());
+    }
   }
 }
 

src/caffe/layers/inner_product_layer.cu

@@ -19,7 +19,9 @@ void InnerProductLayer<Dtype>::Forward_gpu(const vector<Blob<Dtype>*>& bottom,
       caffe_gpu_axpy<Dtype>(N_, bias_multiplier_.cpu_data()[0],
                             this->blobs_[1]->gpu_data(), top_data);
   } else {
-    caffe_gpu_gemm<Dtype>(CblasNoTrans, CblasTrans, M_, N_, K_, (Dtype)1.,
+    caffe_gpu_gemm<Dtype>(CblasNoTrans,
+                          transpose_ ? CblasNoTrans : CblasTrans,
+                          M_, N_, K_, (Dtype)1.,
                           bottom_data, weight, (Dtype)0., top_data);
     if (bias_term_)
       caffe_gpu_gemm<Dtype>(CblasNoTrans, CblasNoTrans, M_, N_, 1, (Dtype)1.,
@@ -36,8 +38,17 @@ void InnerProductLayer<Dtype>::Backward_gpu(const vector<Blob<Dtype>*>& top,
     const Dtype* top_diff = top[0]->gpu_diff();
     const Dtype* bottom_data = bottom[0]->gpu_data();
     // Gradient with respect to weight
-    caffe_gpu_gemm<Dtype>(CblasTrans, CblasNoTrans, N_, K_, M_, (Dtype)1.,
-        top_diff, bottom_data, (Dtype)1., this->blobs_[0]->mutable_gpu_diff());
+    if (transpose_) {
+      caffe_gpu_gemm<Dtype>(CblasTrans, CblasNoTrans,
+          K_, N_, M_,
+          (Dtype)1., bottom_data, top_diff,
+          (Dtype)1., this->blobs_[0]->mutable_gpu_diff());
+    } else {
+      caffe_gpu_gemm<Dtype>(CblasTrans, CblasNoTrans,
+          N_, K_, M_,
+          (Dtype)1., top_diff, bottom_data,
+          (Dtype)1., this->blobs_[0]->mutable_gpu_diff());
+    }
   }
   if (bias_term_ && this->param_propagate_down_[1]) {
     const Dtype* top_diff = top[0]->gpu_diff();
@@ -49,9 +60,17 @@ void InnerProductLayer<Dtype>::Backward_gpu(const vector<Blob<Dtype>*>& top,
   if (propagate_down[0]) {
     const Dtype* top_diff = top[0]->gpu_diff();
     // Gradient with respect to bottom data
-    caffe_gpu_gemm<Dtype>(CblasNoTrans, CblasNoTrans, M_, K_, N_, (Dtype)1.,
-        top_diff, this->blobs_[0]->gpu_data(), (Dtype)0.,
-        bottom[0]->mutable_gpu_diff());
+    if (transpose_) {
+      caffe_gpu_gemm<Dtype>(CblasNoTrans, CblasTrans,
+          M_, K_, N_,
+          (Dtype)1., top_diff, this->blobs_[0]->gpu_data(),
+          (Dtype)0., bottom[0]->mutable_gpu_diff());
+    } else {
+      caffe_gpu_gemm<Dtype>(CblasNoTrans, CblasNoTrans,
+          M_, K_, N_,
+         (Dtype)1., top_diff, this->blobs_[0]->gpu_data(),
+         (Dtype)0., bottom[0]->mutable_gpu_diff());
+    }
   }
 }
 

src/caffe/proto/caffe.proto

@@ -786,6 +786,11 @@ message InnerProductParameter {
   // all preceding axes are retained in the output.
   // May be negative to index from the end (e.g., -1 for the last axis).
   optional int32 axis = 5 [default = 1];
+  // Specify whether to transpose the weight matrix or not.
+  // If transpose == true, any operations will be performed on the transpose
+  // of the weight matrix. The weight matrix itself is not going to be transposed
+  // but rather the transfer flag of operations will be toggled accordingly.
+  optional bool transpose = 6 [default = false];
 }
 
 // Message that stores parameters used by LogLayer