diff --git a/src/lib.rs b/src/lib.rs
index 5b98681..bfef442 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -109,7 +109,10 @@ pub mod traits {
 pub mod rational {
     pub use num_rational::*;
 }
-
+/// A value bounded by a minimum and a maximum
+///
+/// If input is less than min then min is returned, if input is greater than max then max is
+/// returned.  Otherwise input is returned.
 pub fn clamp<T: PartialOrd + Copy>(input: T, min: T, max: T) -> T {
     debug_assert!(min < max, "min must be less than max");
     if input <= min {min}