From b15c99f695a25df05a29cde055e4bd014778d69a Mon Sep 17 00:00:00 2001
From: Will Charczuk <will.charczuk@gmail.com>
Date: Wed, 13 Jul 2016 15:46:51 -0700
Subject: [PATCH] pct diff function

---
 util.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/util.go b/util.go
index 3e18a64..4fefa5c 100644
--- a/util.go
+++ b/util.go
@@ -135,3 +135,9 @@ func Seq(start, end float64, steps ...float64) []float64 {
 	}
 	return values
 }
+
+// PercentageDifference computes the percentage difference between two values.
+// The formula is (v2-v1)/v1.
+func PercentageDifference(v1, v2 float64) float64 {
+	return (v2 - v1) / v1
+}