text: """
  Functions for various arithmetic calculations.
  
  Created: Autumn 2016
  Authors: Petter Lind & David Lindstedt
  """
  
  import numpy as np
  
  
  def run_mean(x, N, mode='valid'):
      """
      Calculate running mean
  
      Return running mean of data vector x where
      N is the window size.
      mode key word argument describes how the edges should be handled.
      See numpy.convolve for more information.
      """
      return np.convolve(x, np.ones((N,))/N, mode='valid')
  