code: def    dbal(c, s, r, l):
      
      ad = 0
      res = []
      for x in range(l):
          if x == (l -1):
              dexp = (c - s -ad)
          else: 
              dexp = (((c)/l)/(c) * r) * (c - ad)
          res.append(dexp)
          ad = ad + dexp
      return res
docs: This accountancy function computes declining balance
      depreciation for an asset purchased for cash with
      a known life span and salvage value.  The depreciation
      is returned as a list in Python.
      c = historcal cost or price paid
      s = the expected salvage proceeds
      r = declining percetage rate(ie 1, 1.2, 1.75 or double 2)
      l = expected useful life of the fixed asset
      Example: dbal(1000, 100, 1.5, 5) for 150% declining
      Example: dbal(1000, 100, 2, 5) for double declining