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
+}