Functor Piecewise_linear.Make_invertible

module Make_invertible: 
functor (Key : Piecewise_linear_intf.Key) -> 
functor (Value : Piecewise_linear_intf.Value) -> S_invertible 
  with type key = Key.t 
  with type value = Value.t

include Piecewise_linear_intf.S

create enforces that the x (key) values are strictly increasing. It also enforces that the y (value) values are either strictly increasing or strictly decreasing. These two properties give us invertibility.

val get_inverse : t -> value -> key

get_inverse t value is the inverse operation of get t key.