Add file test for CUDA installation

Author: trinhgiahuy

hello

@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+__global__
+void saxpy(int n, float a, float *x, float *y)
+{
+  int i = blockIdx.x*blockDim.x + threadIdx.x;
+  if (i < n) y[i] = a*x[i] + y[i];
+}
+
+int main(void)
+{
+  int N = 1<<20;
+  float *x, *y, *d_x, *d_y;
+  x = (float*)malloc(N*sizeof(float));
+  y = (float*)malloc(N*sizeof(float));
+
+  cudaMalloc(&d_x, N*sizeof(float)); 
+  cudaMalloc(&d_y, N*sizeof(float));
+
+  for (int i = 0; i < N; i++) {
+    x[i] = 1.0f;
+    y[i] = 2.0f;
+  }
+
+  cudaMemcpy(d_x, x, N*sizeof(float), cudaMemcpyHostToDevice);
+  cudaMemcpy(d_y, y, N*sizeof(float), cudaMemcpyHostToDevice);
+
+  // Perform SAXPY on 1M elements
+  saxpy<<<(N+255)/256, 256>>>(N, 2.0f, d_x, d_y);
+
+  cudaMemcpy(y, d_y, N*sizeof(float), cudaMemcpyDeviceToHost);
+
+  float maxError = 0.0f;
+  for (int i = 0; i < N; i++)
+    maxError = max(maxError, abs(y[i]-4.0f));
+  printf("Max error: %f\n", maxError);
+
+  cudaFree(d_x);
+  cudaFree(d_y);
+  free(x);
+  free(y);
+}