User Defined Funtion to handle variable number of non-contiguous cells?

[derek-jade]

I simply want to write a UDF which can take the same inputs as most of excel's default formulas.

For example, SUM() allows you to either select a row/column of cells, any number of non-contiguous cells, or a combination thereof.

How can I get my UDF to behave this way?

Is there a way to view the VBA code for the default SUM() formula?

I'm new to UDF's and am trying to write a decibel-summing function.