SYD(cost, salvage, life, period)

Returns the sum-of-years' digits depreciation of an asset (Double).

cost	The initial cost of the asset (Double).
salvage	The value at the end of the depreciation (Double).
life	The length of the useful life of the asset (Double).
period	The period you want to calculate the depreciation over (Double).

REMARKS

* The "life" and "period" arguments must be expressed in the same units.
* If "salvage" < 0, then you will get a run time error.
* If "life" <= 0, then you will get a run time error.
* If "period" <= 0, then you will get a run time error.
* If "period" > "life", then you will get a run time error.
* You can use the DDB function to return the depreciation of an asset in a single period (double or higher declining balance method).
* You can use the SLN function to return the straight-line depreciation of an asset over a single period of time.
* The equivalent Excel function is Application.WorksheetFunction.SYD
* The equivalent .NET function is Microsoft.VisualBasic.Financial.SYD
* For the Microsoft documentation refer to learn.microsoft.com

'the depreciation of a £500 asset over 1 year
Debug.Print Syd(500, 0, 1, 1)         '=  500  

'over 2 years
Debug.Print Syd(500, 0, 2, 1)         '=  333.334, the amount of depreciation in the first year  
Debug.Print Syd(500, 0, 2, 2)         '=  166.667, the amount of depreciation in the second year  

'over 3 years
Debug.Print Syd(500, 0, 3, 1)         '=  250, the amount of depreciation in the first year  
Debug.Print Syd(500, 0, 3, 2)         '=  166.667, the amount of depreciation in the second year  
Debug.Print Syd(500, 0, 3, 3)         '=  83.333, the amount of depreciation in the third year  

'over 4 years
Debug.Print Syd(500, 0, 4, 1)         '= ?  
Debug.Print Syd(500, 0, 4, 2)         '= ?  
Debug.Print Syd(500, 0, 4, 3)         '= ?  
Debug.Print Syd(500, 0, 4, 4)         '= ?