new_contents: import numpy as np
  
  
  def power_method(A, iter_num=1):
      """
      Calculate the first singular vector/value of a target matrix based on the power method.
      Parameters
      ----------
      A : numpy array
          Target matrix
      iter_num : int
                 Number of iterations
  
      Returns
      -------
      u : numpy array
          first left singular vector of A
      s : float
          first singular value of A
      v : numpy array
          first right singular vector of A
      """
      # set initial vector q
      q = np.random.normal(size=A.shape[1])
      q = q / np.linalg.norm(q)
  
      for i in range(iter_num):
          q = np.dot(np.dot(A.T, A), q)
  
      v = q / np.linalg.norm(q)
      Av = np.dot(A, v)
      s = np.linalg.norm(Av)
      u = Av / s
  
      return u, s, v
  
subject: Add utils.py (including the implementation of power method)