The code where the error code occurs is as follows:

'Calculate Production function

Output_t1 = GrowthFactor ^ (Period_Length) * (Output_t0 + FactorProductivity * (1 - Damages_Production_t1) * _

(1 - AbatementCost_Production) * (CapitalStock_t1 - CapitalStock_t0) ^ Share_K_Capital * _

(Labor_t0 ^ Share_Labor))

What's funny is that when I first ran the program it worked several times without error. Then I changed the value of dep_K on the excel sheet and got the message. The program no longer worked even when I changed the value of dep_K back to the original value (actually it worked off and on for a couple of times before it never worked again). I had a backup copy and tried that one, too. Again the exact same results. It worked until I changed the value of dep_K and didn't work even when I changed it back to the original value.

I also played around to see which terms caused the error. Apparently the problem is with (CapitalStock_t1 - CapitalStock_t0). The program runs every time I take that term out. The program runs with all of the remaining variable. I've rewritten the term, but no luck. I've checked to see if I missed declare the terms, but again no luck.

Anyone have any suggestions? What's wrong with this code? This code is embedded in the following double Do Until loops. Maybe there is an error in the loops?

'Calculate Production function

Output_t1 = GrowthFactor ^ (Period_Length) * (Output_t0 + FactorProductivity * (1 - Damages_Production_t1) * _

(1 - AbatementCost_Production) * (CapitalStock_t1 - CapitalStock_t0) ^ Share_K_Capital * _

(Labor_t0 ^ Share_Labor))

What's funny is that when I first ran the program it worked several times without error. Then I changed the value of dep_K on the excel sheet and got the message. The program no longer worked even when I changed the value of dep_K back to the original value (actually it worked off and on for a couple of times before it never worked again). I had a backup copy and tried that one, too. Again the exact same results. It worked until I changed the value of dep_K and didn't work even when I changed it back to the original value.

I also played around to see which terms caused the error. Apparently the problem is with (CapitalStock_t1 - CapitalStock_t0). The program runs every time I take that term out. The program runs with all of the remaining variable. I've rewritten the term, but no luck. I've checked to see if I missed declare the terms, but again no luck.

Anyone have any suggestions? What's wrong with this code? This code is embedded in the following double Do Until loops. Maybe there is an error in the loops?

Code:

```
'Begin Outer Loop XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX End Outer Loop
'The outerloop is the time loop. After variables for a time period is calculated, the program exits the inner loop into the outerloop to update the
'time period.
'Set Counter
Dim t As Long
t = 1
Do Until t = 102
'First the economy flatlines (dies) if the survivability function is zero.
If Survivability_Function_t0 = 0 Then
Output_t1 = 0
CapitalStock_t1 = 0
Consumption_t1 = 0
Investment_t1 = 0
Government_t1 = 0
TotalDeadWtLoss_t1 = 0
Energy_Usage_Consumption_t1 = 0
Energy_Usage_Production_t1 = 0
Energy_Usage_t1 = 0
AtmoEmissions_t1 = 0
CO2_Level_t1 = AtmoEmissions_t1 + (CO2_Equilibrium_Fraction_Atm * (CO2_Level_t0 - CO2_Equilibrium)) + _
((1 - CO2_Equilibrium_Fraction_Atm) * (1 - CO2_TransferRate_to_Atm) * (CO2_Level_t0 - CO2_Equilibrium)) + CO2_Equilibrium
CO2_Transient_t1 = (1 - CO2_Equilibrium_Fraction_Atm) * AtmoEmissions_t1 + (1 - CO2_Equilibrium_Fraction_Atm) * _
(1 - CO2_TransferRate_to_Atm) * (CO2_Level_t0 - CO2_Equilibrium)
New_CO2_Equilibrium_t1 = CO2_Level_t1 - CO2_Transient_t1
Damages_Utility_t1 = 1
Damages_CapitalStock_t1 = 1
Damages_Production_t1 = 1
Damages_Y_Composite_t1 = 1
Damages_Composite_t1 = 1
'If the economy is still living, then proceed through innerloop. Otherwise, go to outerloop.
Else
'Begin Inner Loop xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Begin Inner Loop
'In the inner loop, an iteration process is used to solve for the damages, and production simultaneity problem. First solve the problem using the
'last periods damages, then calculate a new implied damage quantity. Then use the new computed damages to solve for production. Repeat the process until
'a solution converges.
'Declare and set counter
Dim w As Long
w = 1
'Declare and set conditional statement variable
Dim Abs_Error As Double
Abs_Error = 0.1
Do Until Abs_Error < 0.005
'Assume Damages are equal to their last computed values
Damages_CapitalStock_t1 = Damages_CapitalStock_t0
Damages_Utility_t1 = Damages_Utility_t0
Damages_Production_t1 = Damages_Production_t0
Damages_Composite_t1 = Damages_Composite_t0
'Calculate Capital Stock. Remember, damages to capital stock acts like another depreciation rate.
CapitalStock_t1 = Investment_t0 + (1 - Dep_k) ^ Period_Length * (1 - Damages_CapitalStock_t0) ^ Period_Length * CapitalStock_t0
'Calculate Production function
Output_t1 = GrowthFactor ^ (Period_Length) * (Output_t0 + FactorProductivity * (1 - Damages_Production_t1) * _
(1 - AbatementCost_Production) * (CapitalStock_t1 - CapitalStock_t0) ^ Share_K_Capital * _
(Labor_t0 ^ Share_Labor))
'Calculate World Accounting Equation: Consumption, Investment and Government Spending.
Consumption_t1 = (Share_Consumption * Output_t1) * (1 - AbatementCost_Consumption) ^ (1 / (1 + MU_Elasticity))
Investment_t1 = Share_Investment * Output_t1 + (1 - (1 - AbatementCost_Consumption) ^ (1 / (1 + MU_Elasticity)))
Government_t1 = Share_Government * Output_t1
TotalDeadWtLoss_t1 = Output_t1 - Consumption_t1 - Investment_t1 - Government_t1
'Note: AtmoEmissions is the same as retained emissions.
'Energy Balance
Energy_Usage_Consumption_t1 = Energy_to_Consumption_Ratio * Consumption_t1
Energy_Usage_Production_t1 = Energy_to_Production_Ratio * Output_t1
Energy_Usage_t1 = Energy_Usage_Consumption_t1 + Energy_Usage_Production_t1
AtmoEmissions_Consumption_t1 = Emissions_Consumption_Ratio * Consumption_t1
AtmoEmissions_Output_t1 = Emissions_Output_Ratio * Output_t1
AtmoEmissions_t1 = AtmoEmissions_Consumption_t1 + AtmoEmissions_Output_t1
'CO2 Level
CO2_Level_t1 = AtmoEmissions_t1 + (CO2_Equilibrium_Fraction_Atm * (CO2_Level_t0 - CO2_Equilibrium)) + _
((1 - CO2_Equilibrium_Fraction_Atm) * (1 - CO2_TransferRate_to_Atm) * (CO2_Level_t0 - CO2_Equilibrium)) + CO2_Equilibrium
CO2_Transient_t1 = (1 - CO2_Equilibrium_Fraction_Atm) * AtmoEmissions_t1 + (1 - CO2_Equilibrium_Fraction_Atm) * _
(1 - CO2_TransferRate_to_Atm) * (CO2_Level_t0 - CO2_Equilibrium)
New_CO2_Equilibrium_t1 = CO2_Level_t1 - CO2_Transient_t1
'New Temperature Deviation
Dim Temp_Off_t1 As Double
Temperature_Critical = Sheets(1).Range("K28")
Forcing_t1 = 3.35 * (Log(1 + 1.2 * CO2_Level_t1 + 0.005 * CO2_Level_t1 ^ 2 + 1.4 * 10 ^ (-6) * CO2_Level_t1 ^ 3) _
- Log(1 + 1.2 * CO2_Equilibrium + 0.005 * CO2_Equilibrium ^ 2 + 1.4 * 10 ^ (-6) * CO2_Equilibrium ^ 3))
Temp_Off_t1 = ClimateSensitivity_Lambda * Forcing_t1
If Temp_Off_t1 < Temperature_Critical Then
Switch = 0
Else
Switch = 1
End If
Temp_t1 = Temp_Off_t1 + ClimateSensitivityParameter_b2 * Switch * (CO2_Level_t1 / CO2_Equilibrium)
'Damages
Damages_Utility_t1 = 1 - (1 / (1 + Proportional_Constant_Temperature_U * Temp_t1 + Exponent_Constant_Temperature_U * Temp_t1 ^ 2))
Damages_Production_t1 = 1 - (1 / (1 + Proportional_Constant_Temperature_Y * Temp_t1 + Exponent_Constant_Temperature_Y * Temp_t1 ^ 2))
Damages_CapitalStock_t1 = 1 - (1 / (1 + Proportional_Constant_Temperature_K * Temp_t1 + Exponent_Constant_Temperature_K * Temp_t1 ^ 2))
Damages_Y_Composite_t1 = 1 - (1 - Damages_Production_t1) * (1 - Damages_CapitalStock_t1) ^ Share_K_Capital
Damages_Composite_t1 = Damages_Utility_t1 + (1 - Damages_Utility_t1) * Damages_Utility_t1 * (Damages_Y_Composite_t1 ^ MU_Elasticity)
'Begin Error Calculations
'Termination or continuance condition of iteration process. If error is small enough terminate loop. Termination also occurs
'when 100 iteration attempts have been made.
If w = 1 Then
Abs_Error = 0.001
End If
If w > 1 And w < 100 Then
Abs_Error = Abs((Output_t1 - Output_t0) / Output_t0)
End If
If Abs_Error > 0.005 Then
'Reset t1 variables as t0 variables and start at the beginning of the loop.
Damages_CapitalStock_t0 = Damages_CapitalStock_t1
Damages_Utility_t0 = Damages_Utility_t1
Damages_Production_t0 = Damages_Production_t1
Damages_Y_Composite_t0 = Damages_Y_Composite_t0
Damages_Composite_t0 = Damages_Composite_t1
End If
'Termination or continuance condition of iteration process. If error is small enough terminate loop. Termination also occurs
'when 100 iteration attempts have been made.
w = w + 1
Loop
'End Inner Loop xxxxxxxxxxxxxxxxxxxxx'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx End Inner Loop
End If
'Utility and welfare calculations
'Survivability Probability
Survivability_Function_t1 = 1 - (Temp_t1 ^ 2 / (Temp_Max ^ 2 + 1.96 * (Temp_Max - Temp_t1) ^ 2))
If Survivability_Function_t1 <= 0 Then
Temp_t1 = SKI_Limit_Temp
Survivability_Function_t1 = 0
End If
'Utility Index
Raw_Utility_Index_t1 = (Survivability_Function_t1 * (Consumption_t1 ^ MU_Elasticity)) / MU_Elasticity
Utility_Index_t1 = Utility_Normalization_Factor * Raw_Utility_Index_t1
'Welfare
Welfare_t1 = Welfare_t0 + Discount_Factor ^ Period_Length * Utility_Index_t1
'Print output
Sheets(1).Range("P" & 3 + t, "AK" & 3 + t).Value = _
Array(Output_t1, CapitalStock_t1, Consumption_t1, Investment_t1, Government_t1, TotalDeadWtLoss_t1, _
Energy_Usage_Consumption_t1, Energy_Usage_Production_t1, Energy_Usage_t1, AtmoEmissions_t1, CO2_Level_t1, _
CO2_Transient_t1, New_CO2_Equilibrium_t1, Temp_t1, Damages_Utility_t1, Damages_CapitalStock_t1, Damages_Production_t1, _
Damages_Y_Composite_t1, Damages_Composite_t1, Survivability_Function_t1, Utility_Index_t1, Welfare_t1)
'Reset stock variables and survivability function
Investment_t0 = Investment_t1
CapitalStock_t0 = CapitalStock_t1
Output_t0 = Output_t1
CO2_Level_t0 = CO2_Level_t1
Welfare_t0 = Welfare_t1
Survivability_Function_t0 = Survivability_Function_t1
t = t + 1
Loop
```

Last edited by a moderator: