diff --git a/src/main/java/com/clust4j/optimize/OptimizableCaller.java b/src/main/java/com/clust4j/optimize/OptimizableCaller.java
index 2a7ec01..15fe767 100644
--- a/src/main/java/com/clust4j/optimize/OptimizableCaller.java
+++ b/src/main/java/com/clust4j/optimize/OptimizableCaller.java
@@ -23,5 +23,10 @@
  * @param <T>
  */
 public interface OptimizableCaller {
+	/**
+	 * The function whose output to minimize
+	 * @param val
+	 * @return
+	 */
 	public double doCall(double val);
 }