def test_demonstration():
    # change stdout
    print("\nStart plot,please wait!!!")
    sys.stdout = open(os.devnull, "w")

    ax1 = plt.subplot2grid((2, 2), (0, 0))
    ax2 = plt.subplot2grid((2, 2), (0, 1))
    ax3 = plt.subplot2grid((2, 2), (1, 0))
    ax4 = plt.subplot2grid((2, 2), (1, 1))
    ax1.set_title("linear svm,cost:0.1")
    test_linear_kernel(ax1, cost=0.1)
    ax2.set_title("linear svm,cost:500")
    test_linear_kernel(ax2, cost=500)
    ax3.set_title("rbf kernel svm,cost:0.1")
    test_rbf_kernel(ax3, cost=0.1)
    ax4.set_title("rbf kernel svm,cost:500")
    test_rbf_kernel(ax4, cost=500)

    sys.stdout = sys.__stdout__
    print("Plot done!!!")