text: #include <cmath>
  #include <cstring>
  #include <vector>
  
  #include "caffe/blob.hpp"
  #include "caffe/common.hpp"
  #include "caffe/common_layers.hpp"
  #include "caffe/filler.hpp"
  #include "google/protobuf/text_format.h"
  #include "gtest/gtest.h"
  
  #include "caffe/test/test_caffe_main.hpp"
  #include "caffe/test/test_gradient_check_util.hpp"
  
  namespace caffe {
  
  template <typename TypeParam>
  class MVNLayerTest : public MultiDeviceTest<TypeParam> {
    typedef typename TypeParam::Dtype Dtype;
   protected:
    MVNLayerTest()
        : blob_bottom_(new Blob<Dtype>(2, 3, 4, 5)),
          blob_top_(new Blob<Dtype>()) {
      // fill the values
      FillerParameter filler_param;
      GaussianFiller<Dtype> filler(filler_param);
      filler.Fill(this->blob_bottom_);
      blob_bottom_vec_.push_back(blob_bottom_);
      blob_top_vec_.push_back(blob_top_);
    }
    virtual ~MVNLayerTest() { delete blob_bottom_; delete blob_top_; }
    Blob<Dtype>* const blob_bottom_;
    Blob<Dtype>* const blob_top_;
    vector<Blob<Dtype>*> blob_bottom_vec_;
    vector<Blob<Dtype>*> blob_top_vec_;
  };
  
  TYPED_TEST_CASE(MVNLayerTest, TestDtypesAndDevices);
  
  TYPED_TEST(MVNLayerTest, TestForward) {
    typedef typename TypeParam::Dtype Dtype;
    LayerParameter layer_param;
    MVNLayer<Dtype> layer(layer_param);
    layer.SetUp(this->blob_bottom_vec_, this->blob_top_vec_);
    layer.Forward(this->blob_bottom_vec_, this->blob_top_vec_);
    // Test mean
    int num = this->blob_bottom_->num();
    int channels = this->blob_bottom_->channels();
    int height = this->blob_bottom_->height();
    int width = this->blob_bottom_->width();
  
    for (int i = 0; i < num; ++i) {
      for (int j = 0; j < channels; ++j) {
        Dtype sum = 0, var = 0;
        for (int k = 0; k < height; ++k) {
          for (int l = 0; l < width; ++l) {
            Dtype data = this->blob_top_->data_at(i, j, k, l);
            sum += data;
            var += data * data;
          }
        }
        sum /= height * width;
        var /= height * width;
  
        const Dtype kErrorBound = 0.001;
        // expect zero mean
        EXPECT_NEAR(0, sum, kErrorBound);
        // expect unit variance
        EXPECT_NEAR(1, var, kErrorBound);
      }
    }
  }
  
  TYPED_TEST(MVNLayerTest, TestForwardMeanOnly) {
    typedef typename TypeParam::Dtype Dtype;
    LayerParameter layer_param;
    CHECK(google::protobuf::TextFormat::ParseFromString(
        "mvn_param{normalize_variance: false}", &layer_param));
    MVNLayer<Dtype> layer(layer_param);
    layer.SetUp(this->blob_bottom_vec_, this->blob_top_vec_);
    layer.Forward(this->blob_bottom_vec_, this->blob_top_vec_);
    // Test mean
    int num = this->blob_bottom_->num();
    int channels = this->blob_bottom_->channels();
    int height = this->blob_bottom_->height();
    int width = this->blob_bottom_->width();
  
    for (int i = 0; i < num; ++i) {
      for (int j = 0; j < channels; ++j) {
        Dtype sum = 0, var = 0;
        for (int k = 0; k < height; ++k) {
          for (int l = 0; l < width; ++l) {
            Dtype data = this->blob_top_->data_at(i, j, k, l);
            sum += data;
            var += data * data;
          }
        }
        sum /= height * width;
  
        const Dtype kErrorBound = 0.001;
        // expect zero mean
        EXPECT_NEAR(0, sum, kErrorBound);
      }
    }
  }
  
  TYPED_TEST(MVNLayerTest, TestForwardAcrossChannels) {
    typedef typename TypeParam::Dtype Dtype;
    LayerParameter layer_param;
    CHECK(google::protobuf::TextFormat::ParseFromString(
        "mvn_param{across_channels: true}", &layer_param));
    MVNLayer<Dtype> layer(layer_param);
    layer.SetUp(this->blob_bottom_vec_, this->blob_top_vec_);
    layer.Forward(this->blob_bottom_vec_, this->blob_top_vec_);
    // Test mean
    int num = this->blob_bottom_->num();
    int channels = this->blob_bottom_->channels();
    int height = this->blob_bottom_->height();
    int width = this->blob_bottom_->width();
  
    for (int i = 0; i < num; ++i) {
      Dtype sum = 0, var = 0;
      for (int j = 0; j < channels; ++j) {
        for (int k = 0; k < height; ++k) {
          for (int l = 0; l < width; ++l) {
            Dtype data = this->blob_top_->data_at(i, j, k, l);
            sum += data;
            var += data * data;
          }
        }
      }
      sum /= height * width * channels;
      var /= height * width * channels;
  
      const Dtype kErrorBound = 0.001;
      // expect zero mean
      EXPECT_NEAR(0, sum, kErrorBound);
      // expect unit variance
      EXPECT_NEAR(1, var, kErrorBound);
    }
  }
  
  TYPED_TEST(MVNLayerTest, TestGradient) {
    typedef typename TypeParam::Dtype Dtype;
    LayerParameter layer_param;
    MVNLayer<Dtype> layer(layer_param);
    GradientChecker<Dtype> checker(1e-2, 1e-3);
    checker.CheckGradientExhaustive(&layer, this->blob_bottom_vec_,
        this->blob_top_vec_);
  }
  
  TYPED_TEST(MVNLayerTest, TestGradientMeanOnly) {
    typedef typename TypeParam::Dtype Dtype;
    LayerParameter layer_param;
    CHECK(google::protobuf::TextFormat::ParseFromString(
        "mvn_param{normalize_variance: false}", &layer_param));
    MVNLayer<Dtype> layer(layer_param);
    GradientChecker<Dtype> checker(1e-2, 1e-3);
    checker.CheckGradientExhaustive(&layer, this->blob_bottom_vec_,
        this->blob_top_vec_);
  }
  
  TYPED_TEST(MVNLayerTest, TestGradientAcrossChannels) {
    typedef typename TypeParam::Dtype Dtype;
    LayerParameter layer_param;
    CHECK(google::protobuf::TextFormat::ParseFromString(
        "mvn_param{across_channels: true}", &layer_param));
    MVNLayer<Dtype> layer(layer_param);
    GradientChecker<Dtype> checker(1e-2, 1e-3);
    checker.CheckGradientExhaustive(&layer, this->blob_bottom_vec_,
        this->blob_top_vec_);
  }
  
  }  // namespace caffe
  