From a64cf66f4cc9bbfbb4a3252b2ba56f2f60de75b3 Mon Sep 17 00:00:00 2001
From: James Lucas <LucasJ94@hotmail.co.uk>
Date: Sun, 18 Sep 2016 14:36:44 -0700
Subject: [PATCH 1/2] Implementing epsilon function to retrieve EPSILON
 constant

---
 traits/src/float.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/traits/src/float.rs b/traits/src/float.rs
index 66c174c..6b052c3 100644
--- a/traits/src/float.rs
+++ b/traits/src/float.rs
@@ -89,6 +89,18 @@ pub trait Float
     /// ```
     fn min_positive_value() -> Self;
 
+    /// Returns epsilon, a small positive value.
+    ///
+    /// ```
+    /// use num_traits::Float;
+    /// use std::f64;
+    ///
+    /// let x: f64 = Float::epsilon();
+    ///
+    /// assert_eq!(x, f64::EPSILON);
+    /// ```
+    fn epsilon() -> Self;
+
     /// Returns the largest finite value that this type can represent.
     ///
     /// ```
@@ -936,6 +948,11 @@ macro_rules! float_impl {
                 ::std::$T::MIN_POSITIVE
             }
 
+            #[inline]
+            fn epsilon() -> Self {
+                ::std::$T::EPSILON
+            }
+
             #[inline]
             fn max_value() -> Self {
                 ::std::$T::MAX

From 381942eb4f023f11c1c2d92d54f03b92eb6312ea Mon Sep 17 00:00:00 2001
From: James Lucas <LucasJ94@hotmail.co.uk>
Date: Thu, 22 Sep 2016 19:56:44 +0100
Subject: [PATCH 2/2] Adding default implementation

---
 traits/src/float.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/traits/src/float.rs b/traits/src/float.rs
index 6b052c3..757be87 100644
--- a/traits/src/float.rs
+++ b/traits/src/float.rs
@@ -2,6 +2,9 @@ use std::mem;
 use std::ops::Neg;
 use std::num::FpCategory;
 
+// Used for default implementation of `epsilon`
+use std::f32;
+
 use {Num, NumCast};
 
 // FIXME: these doctests aren't actually helpful, because they're using and
@@ -99,7 +102,14 @@ pub trait Float
     ///
     /// assert_eq!(x, f64::EPSILON);
     /// ```
-    fn epsilon() -> Self;
+    ///
+    /// # Panics
+    ///
+    /// The default implementation will panic if `f32::EPSILON` cannot
+    /// be cast to `Self`.
+    fn epsilon() -> Self {
+        Self::from(f32::EPSILON).expect("Unable to cast from f32::EPSILON")
+    }
 
     /// Returns the largest finite value that this type can represent.
     ///