function ucircle(npts)%UCIRCLE  Draws the unit circle%%   UCIRCLE draws the unit circle, using 90 points, and set %   x/y axis to be of equal size%%   UCIRCLE(NPTS) draws the unit circle, using NPTS points%%%%%%%%%%%%%%%%%% ucircle.m %%%%%%%%%%%%%%%%%%%%%   Discrete-Time Control Problems using        %%       MATLAB and the Control System Toolbox   %%   by J.H. Chow, D.K. Frederick, & N.W. Chbat  %%         Brooks/Cole Publishing Company        %%                September 2002                 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%const = 180/pi;if nargin == 0,	npts = 90;enddeltheta = 360/npts;theta = [0:deltheta:360]/const;plot(sin(theta),cos(theta))axis equal%%%%%%%%%%