The Math icon from Figure M2-2 can be selected, resulting in the functions shown in Figure M2-6. Additional icons can be found by selecting the Simulink Extras icon shown in Figure M2-1. Selecting the Additional Linear icon from this group yields the set of icons shown in Figure M2-7. The most useful icon here is the PID Controller. Any icon can be “dragged” into the untitled model workspace. In Figure M2-8, we show the preliminary stage of the construction of a control block diagram, where icons have been dragged from their respective libraries into the untitled model workspace.