code: public int index(int i)
      {
          if(i >= prevSize || i < 0)
              throw new IndexOutOfBoundsException("The size of the previously sorted array/list is " + prevSize + " so index " + i + " is not valid");
          return index.get(i);
      }
docs: Given the index <tt>i</tt> into what would be the sorted array, the index in the unsorted original array is returned. <br>
  If the original array was a double array, <i>double[] vals</i>, then the sorted order can be printed with <br>
  <pre><code>
  for(int i = 0; i &lt; indexTable.{@link #length() length}(); i++)
  System.out.println(vals[indexTable.get(i)]);
  </code></pre>
  @param i the index of the i'th sorted value
  @return the index in the original list that would be in the i'th position