depreciationDb

Evaluates the depreciation of an asset using the fixed-declining balance method.

Synopsis

depreciationDb (cost, salvage, life, period, month)

Required Arguments

float cost (Input)

Initial value of the asset.

float salvage (Input)

The value of an asset at the end of its depreciation period.

int life (Input)

Number of periods over which the asset is being depreciated.

int period (Input)

Period for which the depreciation is to be computed. period cannot be less than or equal to 0, and cannot be greater than life +1.

int month (Input)

Number of months in the first year. month cannot be greater than 12 or less than 1.

Return Value

The depreciation of an asset for a specified period using the fixed-declining balance method. If no result can be computed, NaN is returned.

Description

Function depreciationDb computes the depreciation of an asset for a specified period using the fixed-declining balance method. Routine depreciationDb varies depending on the specified value for the argument period, see table below.

period	Formula
period = 1	$$\mathrm{cost} \times \mathrm{rate} \times \frac{\mathrm{month}}{12}$$
period = life	$$(\mathrm{cost} - \text{total depreciation from periods}) \times \mathrm{rate} \times \frac{12 - \mathrm{month}}{12}$$
period other than 1 or life	$$(\mathrm{cost} - \text{total depreciation from prior periods}) \times \mathit{rate}$$

where

$$\mathit{rate} = 1 - \left(\frac{\mathrm{salvage}}{\mathrm{cost}}\right)^ {\left(\frac{1}{\mathit{life}}\right)}$$

NOTE: rate is rounded to three decimal places.

Example

In this example, depreciationDb computes the depreciation of an asset, which costs $2,500 initially, a useful life of 3 periods and a salvage value of $500, for each period.

from __future__ import print_function
from numpy import *
from pyimsl.math.depreciationDb import depreciationDb

cost = 2500
salvage = 500
life = 3
month = 6

for period in range(1, life + 2):
    db = depreciationDb(cost, salvage, life, period, month)
    print("For period %i, db = $%.2f." % (period, db))

Output

For period 1, db = $518.75.
For period 2, db = $822.22.
For period 3, db = $481.00.
For period 4, db = $140.69.