Suggestion and the recommendation of special functions depreciation

Excel includes 5 formulas to calculate depreciation (SLN,DB,DDB,VDB,SYD) and all of these formulas do not include cells for Starting Date and end date for the cycle to calculate depreciation using it except for VDB formula. For example if we want to calculate depreciation for a specific asset starting from 1st of july,2010 to 31st of December,2015. Using the current existing Excel formulas, depreciation can not be calculated directly. However it is used to calculate depreciation for the whole calendar year starting 1st January till 31st of December not for a partial period starting or ending in different dates. As An example of how complex to calculate depreciation using Excel formulas is SLN method.----------------------------------------------------------------------------------

=IF($A7=1,SLN($A$1,$A$2,$A$3)*((DATEDIF($A$4,DATE(YEAR($A$4),MONTH($A$5),DAY($A$5)),"M")+1)/12),
IF($A7=$A$3+1,
((12-((DATEDIF($A$4,DATE(YEAR($A$4),MONTH($A$5),DAY($A$5)),"M")+1)))/12)*SLN($A$1,$A$2,$A$3),SLN($A$1,$A$2,$A$3)))

so I hope and recommend that every supervisor in the Arabic blog to help and support to add two more cells to depreciation formulas *Starting date *End date These recommendation make depreciation formulas more useful and matching the accounting the standards whereas depreciation expense is a major expense and miscalculating it leads to disaster. Best regards