% File:   mcircles.m
% Author: S. A. Bortoff
% Date:   November 11, 1996
% Description: Plots m-circles, which are the locus of constant
% magnitude for the closed-loop transfer function, on the Nyquist Plot, 
% for the values in vector M.  The vector M can be changed.

M=[1/10 1/5 1/3 1/2 1/1.7 1/1.5 1/1.3 1/1.1 1.1 1.3 1.5 1.7 2 3 5 10]

s = (0:628)/100;  % points for the circles
for i=1:length(M),
	radius=M(i)/(M(i)^2-1);
	offset=M(i)^2/(M(i)^2-1);
	x=radius*sin(s)-offset;
	y=radius*cos(s);
	hold on;
	plot(x,y,':');
end