The Excel Delta function tests two numbers for equality and returns the Kronecker Delta. i.e. the function returns 1 if the two supplied numbers are equal and 0 otherwise.
The syntax of the function is :
where number1 and [number2] are the two numbers to be compared. The [number2] argument is optional, and if omitted, takes on the value 0.
four examples of the Excel Delta function are shown in the spreadsheets below.
The spreadsheet on the left shows the formulas and the spreadsheet on the left shows the Delta function results.
Formulas:

Results:

Note that, in cell A4 the above example spreadsheet, second argument, [number2], is omitted from the function. This function therefore compares the supplied value with zero.
Further examples of the Excel Delta function can be found on the Microsoft Office website.
If you get an error from the Excel Delta function this is likely to be one of the following :
#VALUE!    Occurs if any of the supplied number arguments are not numeric 
#NAME?   
Occurs when Analysis ToolPak addin is not enabled in your Excel. + Show How to Do This in Excel 2003: 