Excel Named Function Parameters or UDF without Macros - excel

Question

It seems like a bit of an omission that there's no easy way to create a user-defined declarative function in Excel without defining a macro. I can't use XSLM with the uphill battle that will entail in the Enterprise, but I want to be able to define a function with intent thus.
I want to do this;
=BreakEven(C1:C20)
But I can't use a macro, although I can use a "named formula". The trouble is how to pass parameters to that? I've seen a couple of tricks (kludgy workarounds) but not for xslx.
I'd like to be able to define a Breakeven() function in another tab and reference it here passing in MORE THAN one parameter, two ranges in fact. I'm sure there's some way using string parsing but I can't see it.
I don't mind if the function doesn't look exactly like that, as long as it evaluates within the cell and I can parse it for 'intent'. For instance, this example (http://www.jkp-ads.com/articles/ExcelNames09.asp) which I was unable to get to work in xlsx uses this syntax;
=IF(ROW(D3),CellColor)
Where "cellcolor" is the name of the function and D3 is the range parameter. The other solution I'm toying with is to define a function in column format with a variable argument list (this is two rows of an excel spreadsheet);
[Value][function][parameter1][parameter2][parameter3]
24050 BreakEven C1:C20 A1:A20
It's not pretty, but the benefit of the latter is that it describes the function to an external reader. We know it's a breakeven function, whereas if we put the actual formula "OFFSET,INDIRECT,SUM()()()()etc" it would not be readable/parseable. Of course, in that case, I'd have to construct the value field by parsing the cells to the right in Excel, which would make the Value formula messy but at least it would be a self-describing row.
Can anyone suggest a better method?

Answer 1

Poor-man's UDF
So I think what we're going to have to do is this;
A B C D E
1 [Value][function][parameter1][parameter2][parameter3]
2 24050 BreakEven C1:C20 A1:A20
3 111 mySum 1 10 100
Where "BreakEven" is a "named function". Here's the formula for "mySum";
=sum(C1:E1)
To evaluate functions listed in B, we just put this in column A (transposing the same value for all rows in column A;
=value(B)
This works because A2 and A3 both evaluate column B as a value, which causes BreakEven and Sum to run (as poor-man's UDFs) in the context of A2 and A3. The range (C1:E1) is relative of course.
So in effect, we can write any function name in column B (as long as there's a corresponding named function defined in the workbook which can be as complex as you like). Columns C, D and E act as the parameters for the function on the same row.
I would have loved to just be able to write the following in column A instead;
=mySum(1,10,100)
But in the absence of that support, the mechanism above serves to provide a readable parameterised function that would be understandable by a user, that's also machine readable (works in CSV too) and allows us to offload our re-usable functions to a library sheet somewhere in the workbook for maintenance.
Not perfect, but an acceptable compromise, unless anyone has a clever way of doing this in a single cell?

Answer 2

Not really an answer, but easier to illustrate here than in a comment. Although you can't rename formulas in a simplistic way - I like your suggestion actually I've never thought about that before; but then I've never worked in a non-macro environment so this has never occurred- you can add notes into the actual formula explaining what it does. For example:
=N("This is a really complex BreakEven Formula")+SUM(3,4,5)
Is a perfectly valid formula. As I said, not really an answer, but could potentially add clarity to a complex formula

Answer 3

You can do this with a small trick
For example to create effectively a cuberoot UDF that emulates =cuberoot(x) then name a variable as cuberoot with a 'value' like this.
=(RC[-1])^(1/3)
Now you can either do this using a temporary switch to RC mode, or put the cursor in say cell E5 and type the name value as =(D5)^(1/3)
Now whenever you need a cuberoot you can put the argument in any cell and put =cuberoot in the cell to its right. It really works and follows true Excel rules.
I use it for multiparameter models that have the single 'argument' Time as a dependent variable. I then define the term Model as the model equation eg =a+bTime+cTime^2
where a,b,c are already named locations holding unique parameter values -
and then define Time as =RC[-1]
My sheets are filled with cells simply saying =Model and have the required time value to the left (ie their argument). It is simple to extend to multi arg functions using multiple cells. It usually fits in well with spreadsheet layouts. Change the definition of your model once in the define name box and all places change simultaneously.
I have a function called ToDMS which takes the decimal degree value in the preceding cell and converts it to a deg Min and Sec string - very tidy.
You need the degrees to be in a single cell but want it in the alt. form in another cell
elegant, simple and it works
Bob Jordan