text: """
  
  Auxiliary file
  ==============================================
  
  """
  import numpy as np
  
  domain = np.linspace(0, 10, 50)
  
  
  def model_quadratic(theta):
      # this one takes one parameter vector theta and return one qoi
      inpt = np.array(theta).reshape((-1,))
      return inpt[0] * domain + inpt[1] * domain ** 2
  
  
  def model_linear(theta):
      # this one takes one parameter vector theta and return one qoi
      inpt = np.array(theta).reshape((-1,))
      return inpt[0] * domain
  
  
  def model_cubic(theta):
      # this one takes one parameter vector theta and return one qoi
      inpt = np.array(theta).reshape((-1,))
      return inpt[0] * domain + inpt[1] * domain ** 2 + inpt[2] * domain ** 3