Use of Derivative()

I’m trying to get the first derivative of given signal, which is stored in an array, using ROOT Derivative(). I’ve developed my own algorithm for this purpose but I’d like to use the ROOT one. It is straightforward to do it directly on a given function (some examples are available online), but I’ve got problems when using the array. I’ve unsuccessfully tried to convert the array containing the signal into a function TF1 and then use the Derivative(). Any advise will be welcome, just to point out that the data I’m using is stored in an array.