Consider a type 1 system with the open-loop transfer function:

as shown below:

**To generate the Nyquist
plot**

1.
Create the above diagram using a **const**, t**ransferFunction**, and plot
block.

2. Enter the following polynomial coefficients to the transferFunction block:

Numerator: 1

Denominator: 1 1 0

**Note:** Always leave spaces
between coefficient values.

3.
Choose **System >** **Go**, or click in the toolbar to simulate the diagram.

4.
Select the **transferFunction** block.

5.
Choose **Analyze** **>** **Nyquist** **Response**.

6.
You are reminded that the system has poles on the imaginary axis, which will
result in Nyquist circles at infinity. Click **OK**, or press
**ENTER**.

7.
In the **Nyquist** dialog box, you have the option to change the maximum
frequency range. The default value is 10. Leave it unchanged and click
**OK**, or press **ENTER**.

8. The Nyquist plot appears.

9. Drag on its borders to adjust its size.

You can observe that the point (-1,0) is not enclosed by
the Nyquist contour. Consequently *N* ≤ 0. The poles of *GH*(*s*)
at *s* = 0 and *s* = -1, neither of which are in the right-half plane,
which means that *P* = 0. Therefore, *N* = -*P* = 0 and the
system is absolutely stable.