MATH-552

Fixed bug in "MultidimensionalCounter". Thanks to James Bence.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1087637 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/math/util/MultidimensionalCounter.java

@@ -234,13 +234,7 @@ public class MultidimensionalCounter implements Iterable<Integer> {
             indices[i] = idx;
         }
 
-        int idx = 1;
-        while (count < index) {
-            count += idx;
-            ++idx;
-        }
-        --idx;
-        indices[last] = idx;
+        indices[last] = index - count;
 
         return indices;
     }

src/site/xdoc/changes.xml

@@ -52,6 +52,9 @@ The <action> type attribute can be add,update,fix,remove.
     If the output is not quite correct, check for invisible trailing spaces!
      -->
     <release version="3.0" date="TBD" description="TBD">
+      <action dev="erans" type="fix" issue="MATH-552" due-to="James Bence">
+        Fixed bug in "MultidimensionalCounter".
+      </action>
       <action dev="luc" type="fix" issue="MATH-423" due-to="Gilles Sadowski" >
         All unit tests have been converted to Junit 4. They need at least Junit 4.5 to run
         (the ant and maven build systems are currently set to use Junit 4.8.2)

src/test/java/org/apache/commons/math/util/MultidimensionalCounterTest.java

@@ -121,20 +121,32 @@ public class MultidimensionalCounterTest {
 
     @Test
     public void testIterationConsistency() {
-        final MultidimensionalCounter c = new MultidimensionalCounter(2, 3, 2);
+        final MultidimensionalCounter c = new MultidimensionalCounter(2, 3, 4);
         final int[][] expected = new int[][] {
             { 0, 0, 0 },
             { 0, 0, 1 },
+            { 0, 0, 2 },
+            { 0, 0, 3 },
             { 0, 1, 0 },
             { 0, 1, 1 },
+            { 0, 1, 2 },
+            { 0, 1, 3 },
             { 0, 2, 0 },
             { 0, 2, 1 },
+            { 0, 2, 2 },
+            { 0, 2, 3 },
             { 1, 0, 0 },
             { 1, 0, 1 },
+            { 1, 0, 2 },
+            { 1, 0, 3 },
             { 1, 1, 0 },
             { 1, 1, 1 },
+            { 1, 1, 2 },
+            { 1, 1, 3 },
             { 1, 2, 0 },
-            { 1, 2, 1 }
+            { 1, 2, 1 },
+            { 1, 2, 2 },
+            { 1, 2, 3 }
         };
 
         final int totalSize = c.getSize();