fixed an index error triggering ArrayIndexOutOfBoundException for an add after a clear

if size has grown

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@796021 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/math/util/ResizableDoubleArray.java

@@ -375,6 +375,7 @@ public class ResizableDoubleArray implements DoubleArray, Serializable {
      */
     public synchronized void clear() {
         numElements = 0;
+        startIndex = 0;
         internalArray = new double[initialCapacity];
     }
     

src/test/org/apache/commons/math/stat/descriptive/DescriptiveStatisticsTest.java

@@ -75,6 +75,17 @@ public class DescriptiveStatisticsTest extends TestCase {
             // expected
         }
     }
+
+    public void test20090720() {
+        DescriptiveStatistics descriptiveStatistics = new DescriptiveStatistics(100);
+        for (int i = 0; i < 161; i++) {
+            descriptiveStatistics.addValue(1.2);
+        }
+        descriptiveStatistics.clear();
+        descriptiveStatistics.addValue(1.2);
+        assertEquals(1, descriptiveStatistics.getN());
+    }
+
     public void testRemoval() {
 
         final DescriptiveStatistics dstat = createDescriptiveStatistics();