Code covered by the BSD License

### Katie Singleton (view profile)

MATLAB and Simulink files for textbook Nise/Controls 6e.

ch13p7.m
```% Nise, N.S.
% Control Systems Engineering, 5th ed.
% John Wiley & Sons, Hoboken, NJ, 07030
%
% Control Systems Engineering Toolbox Version 5.0
% Copyright  2008 by John Wiley & Sons, Inc.
%
% (ch13p7) Example 13.10:    We now use the root locus to find the gain for
% stability. First, we create a digital LTI transfer-function object for
% G(z) = N(z)/D(z), with an unspecified sampling interval. The LTI object is created
% using tf(numgz,dengz,[]), where numgz represents N(z), dengz represents D(z),
% and [] indicates an unspecified sampling interval. MATLAB produces a z-plane root
% locus along with the unit circle superimposed using the command, zgrid([],[]).
% We then interactively select the intersection of the root locus
% and the unit circle. MATLAB responds with the value of gain and the closed-loop
% poles. Let us look at Example 13.10.

'(ch13p7) Example 13.10'            % Display label.
clf                                 % Clear graph.
numgz=[1 1];                        % Define numerator of G(z).
dengz=poly([1 0.5]);                % Define denominator of G(z).
'G(z)'                              % Display label.
Gz=tf(numgz,dengz,[])               % Create and display G(z).
rlocus(Gz)                          % Plot root locus.
zgrid([],[])                        % Add unit circle to root locus.
title(['z-Plane Root Locus'])       % Add title to root locus.
[K,p]=rlocfind(Gz)                  % Allows input of K by selecting
% point on graphic.
```