from any block, to exit this mode.
Analyze > Select Input/Output Points lets you choose the input and output reference points for the linearization. If you don’t choose reference points, arbitrary points are chosen when the system is linearized. Unless you’re linearizing a SISO (single input/single output) system, you should use Select Input/Output Points to ensure that the proper input and output points are selected.
Alternate way to select reference points: You can also select reference points with Analyze > Linearize.
To select reference points
1. Choose Analyze > Select Input/Output Points.
The pointer becomes a crossbar.
2. To select an input reference point, point to the output connector on the block that produces the signal with which you want to linearize the system and click the mouse.
The output connector changes color. If the connector you select is invalid, you hear a beep.
3. To select an output reference point, point-and-click over the input connector on the block that consumes the signal against which you wish to linearize.
The input connector changes color. If the connector you select is invalid, you hear a beep.
4.
Click over empty screen, and at least from any block, to exit this mode.
5. The system is linearized with respect to the selected reference points.
To cancel a reference point selection
1. Choose Analyze > Select Input/Output Points.
2. The pointer becomes a crossbar.
3. Point to the selected connector and right-click.
4.
Click over empty screen, and at least 
from any block, to exit this
mode.