Modeling Depreciation

To model depreciation, two inputs are required: 1) a schedule of spend to be depreciated 2) a depreciation schedule

For this example, the index time is 10 year series with

Constant startYear=2008
Time:=Sequence (startYear,startYear+9,1)

Example depreciation schedule is a 5yr MACRS depreciation schedule entered as a variable:

Table(time)(.2,.32,.192,.1152,.1152,.0576,0,0,0,0)

SpendOverTime is a variable indexed by time with the capital spend amounts as desired:

Table(time)(0,0,111,0,0,0,0,0,0,0)

Create a user defined function:

Function_Depreciation,
Parameters: (SpendOverTime,DepreciationSchedule),
Definition: 
    index depr_years = copyindex(time); 
    var deprStartyr:=time;
    sum(if time-depr_years+1<1 then 0 else
    slice(SpendOverTime,time,Depr_years-startYear+1)*slice(depreciationSchedule,time,time-depr_years+1),depr_years)

Then create a depreciation test variable to check the result

Variable: DepreciationTest  
definition: function_Depreciation(spendOverTime,DepreciationSchedule)