Do a Web search on Extrapolation. You really need to think about what you want to do, and to have some idea about the math involved.
To help you clarify your thinking, suppose you have data collected over a period of time (the interval does not matter -- it could be long or short). For the sake of argument, suppose you had 288 values collected more-or-less hourly for 12 days.
Judging only from the data, tell me what the value would have been if you made a measurement on the half-hour after 5 days. Draw out the problem (a lot of programs start with "diagrams on a napkin") and think about how you would come up with a value that was "in the middle" of the data points you already had taken.
Now think about how you would estimate (aha! that word, itself, should give you a clue which textbooks you need to study) the value you would get an hour after you took the final (288th) reading. How about a reading the next day? Generalize.
Once you understand the operations you would need to perform, you can think about how to use LabVIEW to do them. Don't expect that there is a LabVIEW VI specifically designed to solve each of your tasks -- sometimes we need to write them ourselves.
Bob Schor
