code: def _reldiff(a, b):
      
  
      a = float(a)
      b = float(b)
      aa = abs(a)
      ba = abs(b)
  
      if a == 0.0 and b == 0.0:
          return 0.0
      elif a == 0 or b == 0.0:
          return float('inf')
  
      return abs(a - b) / min(aa, ba)
docs: Computes the relative difference of two floating-point numbers
  
      rel = abs(a-b)/min(abs(a), abs(b))
  
      If a == 0 and b == 0, then 0.0 is returned
      Otherwise if a or b is 0.0, inf is returned.