####### PLOTTING THE GRAPH ########
# import matplotlib.pyplot as plt
# i_above = np.where(y >= 0)
# i_below = np.where(y < 0)
# plt.title("Circular dataset")
# plt.scatter(X[i_below,1], X[i_below,2])
# plt.scatter(X[i_above,1], X[i_above,2])
# plt.legend(["-1", "+1"])
# plt.show()