The goal is to call  it from another VBA function, but for now I'm
testing it out by calling it in Excel to see if I'm writing it correctly.

Basically, I have a function  (call it MainFunc) that, depending on
certain conditions, needs to use the log  of the range  as opposed to
the range itself. So I'm trying to create a separate function (call
it LogFunc) that will take in the range of data, apply the log to each
value in the range, and then return the new range back to MainFunc.

Function MainFunc(range_data)
if <condition>
LogFunc(range_data)
end if
End Function

Function LogFunc(range_data)
<this is the problem function>
End Function