Add utils vector mean function

test/utils/test_vector.cu

@@ -0,0 +1,39 @@
+#include <gtest/gtest.h>
+
+#include "vector.cuh"
+
+TEST(VectorTest, TestVectorMean) {
+
+    cudaError_t cudaStatus;
+    float length = 10;
+
+    std::vector<float> input = {0.44371f, 0.20253f, 0.73232f, 0.40378f, 0.93348f, 0.72756f, 0.63388f, 0.5251f, 0.23973f, 0.52233f};
+
+    float* d_vec = nullptr;
+    cudaStatus = cudaMalloc((void **)&d_vec, sizeof(float) * length);
+    EXPECT_EQ(cudaStatus, cudaSuccess);
+
+    float* d_mean = nullptr;
+    cudaStatus = cudaMalloc((void **)&d_mean, sizeof(float) * length);
+    EXPECT_EQ(cudaStatus, cudaSuccess);
+    
+    float* d_length = nullptr;
+    cudaStatus = cudaMalloc((void **)&d_length, sizeof(float));
+    EXPECT_EQ(cudaStatus, cudaSuccess);
+
+    cudaStatus = cudaMemcpy(d_vec, input.data(), sizeof(float) * length, cudaMemcpyHostToDevice);
+    EXPECT_EQ(cudaStatus, cudaSuccess);
+
+    cudaStatus = cudaMemcpy(d_length, &length, sizeof(float), cudaMemcpyHostToDevice);
+    EXPECT_EQ(cudaStatus, cudaSuccess);
+
+    CUDANet::Utils::mean(d_vec, d_mean, d_length, length);
+
+    std::vector<float> mean(length);
+    cudaStatus = cudaMemcpy(mean.data(), d_mean, sizeof(float) * length, cudaMemcpyDeviceToHost);
+    EXPECT_EQ(cudaStatus, cudaSuccess);
+
+    float expected_mean = 0.5364f;
+    EXPECT_NEAR(mean[0], expected_mean, 1e-4);
+
+}