text: # 倒山峰形
  import numpy as np
  from matplotlib import pyplot as plt
  fig = plt.figure()
  ax = plt.axes(projection="3d")
  x = y = np.arange(start=-4, stop=4, step=0.1)
  X, Y = np.meshgrid(x, y)
  Z = X**2+Y**2
  ax.plot_surface(X,Y,Z,alpha=0.9, cstride=1, rstride = 1, cmap='rainbow')
  plt.show()
  exit()
  
  
  #峰值函数上半轴
  import numpy as np
  from matplotlib import pyplot as plt
  fig = plt.figure()
  ax = plt.axes(projection="3d")
  x = y = np.arange(start=-4, stop=4, step=0.1)
  X, Y = np.meshgrid(x, y)
  Z = 3 * (1-X)**2 * np.exp(-X**2-(Y+1)**2)- 10 * (X/5- X**3 - Y**5)*np.exp(-X**2-Y**2)-1/3*np.exp(-(X+1)**2-Y**2)
  Z[Z<0]=0
  ax.plot_surface(X,Y,Z,alpha=0.9, cstride=1, rstride = 1, cmap='rainbow')
  plt.show()
  exit()
  
  # 峰值函数全貌
  import numpy as np
  from matplotlib import pyplot as plt
  fig = plt.figure()
  ax = plt.axes(projection="3d")
  x = y = np.arange(start=-4, stop=4, step=0.1)
  X, Y = np.meshgrid(x, y)
  Z = 3 * (1-X)**2 * np.exp(-X**2-(Y+1)**2)- 10 * (X/5- X**3 - Y**5)*np.exp(-X**2-Y**2)-1/3*np.exp(-(X+1)**2-Y**2)
  ax.plot_surface(X,Y,Z,alpha=0.9, cstride=1, rstride = 1, cmap='rainbow')
  plt.show()
  exit()
  