Corrected error in exception text.

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@556484 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/math/random/RandomDataImpl.java

@@ -380,7 +380,7 @@ public class RandomDataImpl implements RandomData, Serializable {
     public double nextUniform(double lower, double upper) {
         if (lower >= upper) {
             throw new IllegalArgumentException
-            ("lower bound must be <= upper bound");
+            ("lower bound must be < upper bound");
         }
         RandomGenerator rand = getRan();