Dav is correct. You can add named ranges that perform functions. Named ranges don't have to refer to actual ranges on your worksheet. For instance:
The redline is actual data. The blue line is a named range:
That range performs a (very simple) function on a range. Its result is an array the same size as the source range. If you do something like
SUM(Range) it returns a single value and, thus, would only chart a single value. So long as you stick to functions that return arrays, it should work fine. I don't know what kind of operation you want to do, though, so it's possible that it won't work for whatever reason.
The only other oddity is when you go to add the series to the chart. You have to add the workbook name if it's a workbook-level name or the sheet name if it's local. That should update as you change workbook / worksheet names, though, so you can set it and forget it. However, if you ever copy that chart to some other file, you might be confused about why it's showing the wrong data until you remember that reference.