Modern control engineering

The polar plot of a sinusoidal transfer function G(jv) is a plot of the magnitude of G(jv) versus the phase angle of G(jv) on polar coordinates as v is varied from zero to infinity.Thus, the polar plot is the locus of vectors as v is varied from zero to infinity. Note that in polar plots a positive (negative) phase angle is measured counterclockwise (clockwise) from the positive real axis.The polar plot is often called the Nyquist plot.An example of such a plot is shown in Figure 7–25. Each point on the polar plot of G(jv) represents the terminal point of a vector at a particular value of v. In the polar plot, it is important to show the frequency graduation of the locus. The projections of G(jv) on the real and imaginary axes are its real and imaginary components. @G(jv) @ /G(jv) If we replace the command bode(A,B,C,D) in MATLAB Program 7–4 with