### Question:
MatrixSeries extends Series implements Serializable { public int getItemColumn(int itemIndex) { return itemIndex % getColumnsCount(); } MatrixSeries(String name, int rows, int columns); int getColumnsCount(); Number getItem(int itemIndex); int getItemColumn(int itemIndex); @Override int getItemCount(); int getItemRow(int itemIndex); int getRowCount(); double get(int i, int j); void update(int i, int j, double mij); void zeroAll(); @Override boolean equals(Object obj);  }### Answer:
@Test public void testGetItemColumn() { MatrixSeries m = new MatrixSeries("Test", 3, 2); assertEquals(0, m.getItemColumn(0)); assertEquals(1, m.getItemColumn(1)); assertEquals(0, m.getItemColumn(2)); assertEquals(1, m.getItemColumn(3)); assertEquals(0, m.getItemColumn(4)); assertEquals(1, m.getItemColumn(5)); }