Averages/Arithmetic mean: Difference between revisions

=={{header|F_Sharp|F#}}==

The following computes the running mean using a tail-recursive approach. If we just sum all the values then divide by the number of values then we will suffer from overflow problems for large lists. See [http://en.wikipedia.org/wiki/Moving_average wikipedia] about the moving average computation.

let avg (a:float) (v:float) n =

a + (1. / ((float n) + 1.)) * (v - a)

let mean_series list =

let rec f a n list =

match list with

| [] -> a

| h :: t -> f (avg a (float h) n) (n + 1) t

f 0. 0 list

Checking this:

> mean_series [1; 8; 2; 8; 1; 7; 1; 8; 2; 7; 3; 6; 1; 8; 100] ;;

val it : float = 10.86666667

> mean_series [] ;;

val it : float = 0.0