text: import numpy as np
  import matplotlib.pylab as plt
  
  def step_function(x):
      return np.array(x > 0, dtype=np.int)
  
  x = np.arange(-5.0, 5.0, 0.1)
  y = step_function(x)
  plt.plot(x, y)
  plt.ylim(-0.1, 1.1) # y축의 범위 지정
  plt.show()