When running the routine, is it typically the function that changes or the input data that changes?
If it's the same function running on different data, then you are applying the function to the data. If it's the same data running in a different function, then you are applying the data to the function.
If it's the same function running on different data, then you are applying the function to the data. If it's the same data running in a different function, then you are applying the data to the function.