#include <vector>

#include "caffe/sgd_solvers.hpp"

namespace caffe {

#ifndef CPU_ONLY

template <typename Dtype>

void nesterov_update_gpu(int N, Dtype* g, Dtype* h, Dtype momentum,

Dtype local_rate);

#endif

template <typename Dtype>

void NesterovSolver<Dtype>::ComputeUpdateValue(int param_id, Dtype rate) {

const vector<Blob<Dtype>*>& net_params = this->net_->learnable_params();

const vector<float>& net_params_lr = this->net_->params_lr();

Dtype momentum = this->param_.momentum();

Dtype local_rate = rate * net_params_lr[param_id];

switch (Caffe::mode()) {

case Caffe::CPU: {

// save history momentum for stepping back

caffe_copy(net_params[param_id]->count(),

this->history_[param_id]->cpu_data(),

this->update_[param_id]->mutable_cpu_data());

// update history

caffe_cpu_axpby(net_params[param_id]->count(), local_rate,

net_params[param_id]->cpu_diff(), momentum,

this->history_[param_id]->mutable_cpu_data());

// compute update: step back then over step

caffe_cpu_axpby(net_params[param_id]->count(), Dtype(1) + momentum,

this->history_[param_id]->cpu_data(), -momentum,

this->update_[param_id]->mutable_cpu_data());

// copy

caffe_copy(net_params[param_id]->count(),

this->update_[param_id]->cpu_data(),

net_params[param_id]->mutable_cpu_diff());

break;

}

case Caffe::GPU: {

#ifndef CPU_ONLY

nesterov_update_gpu(net_params[param_id]->count(),

net_params[param_id]->mutable_gpu_diff(),

this->history_[param_id]->mutable_gpu_data(),

momentum, local_rate);

#else

NO_GPU;

#endif

break;

}

default:

LOG(FATAL) << "Unknown caffe mode: " << Caffe::mode();

}

}

INSTANTIATE_CLASS(NesterovSolver);

REGISTER_SOLVER_CLASS(Nesterov);

} // namespace caffe