if n1 = n2 && n1 = n3 then Array.init n1 (fun i -> f a.(i) b.(i) c.(i))
else raise (Invalid_argument "Array.map3 size not matched.");;
if n1 = n2 && n1 = n3 then Array.init n1 (fun i -> f a.(i) b.(i) c.(i))
else raise (Invalid_argument "Array.map3 size not matched.");;