code: def center_eigenvalue_diff(mat):
      """Compute the eigvals of mat and then find the center eigval difference."""
      N = len(mat)
      evals = np.sort(la.eigvals(mat))
      diff = np.abs(evals[N / 2] - evals[N / 2 - 1])
      return diff
  
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: center_eigenvalue_diff(mat) and returns: diff