Do you mean a formula function, rather than a feature? If you mean the former, this might be achievable using SUBSET functions. If the latter, does moving average in the Graph view Line options help?
I am having difficulty creating a rolling/dynamic/moving average/total using SUBSET functions.
I have attached a file with daily data and would like to create an annual moving total. It would be greatly appreciated if someone could show me the best way to do it.