Collections
You can also create a ListMatrix instead of an ArrayList. A ListMatrix behaves like a java.List but is a Matrix at the same time:
ListMatrix S = new DefaultListMatrix(); // List methods: S.add(0.5); S.clear(); // Matrix methods: S.exportToFile(someFile); S.showGUI(); Matrix P = S.plus(5).times(2); // but: P is not a ListMatrix anymore
The same works also for maps:
MapMatrix map = new DefaultMapMatrix();
map.put(key,o);
