code: def energy(input_vector):
      input_vector = np.array(input_vector)
      X = np.array([[1, -1], [-1, 1]])
      weight = X.T.dot(X) - 2 * np.eye(2)
      return -0.5 * input_vector.dot(weight).dot(input_vector)
  
imports: import numpy
  import matplotlib.pyplot
  from mpl_toolkits.mplot3d import Axes3D
label_desc: Use image node_id 1 for calling a global function with example usage: energy(input_vector) and returns: unknown