text: """
  Function: Find Mean, Variance, Standard Variance of X(discrete random variables)
  Coding: utf-8
  Author: fox2049
  Date: 2020/11/10
  """
  
  import numpy as np  # using version-1.19.3 if you are Windows PC
  import math
  
  
  def arr_input():
      array = []
      while True:
          num = input("Input variable or end:")
          if num == "end":
              break
          else:
              array.append(float(num))
              print(array, "-" * 10,len(array))
      return array
  
  
  def sum_ln(ar):
      sum1 = 0
      for num in ar:
          ln = math.log(num, math.e)
          sum1 += ln
      return sum1
  
  
  def var(ar):
      sum2 = 0
      for num in ar:
          dis = num - np.mean(ar)
          sum2 += dis * dis
      return sum2/(len(ar) - 1)
  
  
  if __name__ == '__main__':
      # arr = arr_input()
      arr = [35, 16, 15, 17, 17, 30, 11, 16, 19, 24]
      arr_mean = np.mean(arr)
      arr_var = var(arr)
      arr_std = var(arr) ** 0.5
      print("Mean: %f" % arr_mean)
      print("Variance (unbiased): %f" % arr_var)
      print("Std_Variance (unbiased): %f" % arr_std)
  
  
  
  
  
  
  