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
Parameters:
Key : Piecewise_linear_intf.Key
Value : Piecewise_linear_intf.Value

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.