The Biocaml Library : Biocaml_roc.auc

let auc points = match Stream.next points with

  None -> 0.

 | Some p ->

  Stream.fold

   points

   ~f:(fun ((x1,y1), sum) ((x2,y2) as p) -> 

    (p, sum +. trapez_area x1 x2 y1 y2))

   ~init:(p, 0.)

  |! snd