Usage of factory method is recommended.

Thanks to "ranjan1423".

Closes #165.
diff --git a/src/main/java/org/apache/commons/math4/util/MathUtils.java b/src/main/java/org/apache/commons/math4/util/MathUtils.java
index 3031465..10dc1fe 100644
--- a/src/main/java/org/apache/commons/math4/util/MathUtils.java
+++ b/src/main/java/org/apache/commons/math4/util/MathUtils.java
@@ -59,7 +59,7 @@
      * @return the hash code
      */
     public static int hash(double value) {
-        return new Double(value).hashCode();
+        return Double.valueOf(value).hashCode();
     }
 
     /**
@@ -68,10 +68,10 @@
      *
      * @param x Value
      * @param y Value
-     * @return {@code new Double(x).equals(new Double(y))}
+     * @return {@code Double.valueOf(x).equals(Double.valueOf(y))}
      */
     public static boolean equals(double x, double y) {
-        return new Double(x).equals(new Double(y));
+        return Double.valueOf(x).equals(Double.valueOf(y));
     }
 
     /**