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    %% Frequency Response of a SISO System  
% This example shows how to plot the frequency response and obtain frequency
% response data for a single-input, single-output (SISO) dynamic system model.   

%% 
% Create a transfer function model and plot its frequency response. 
H = tf([10,21],[1,1.4,26]); 
bode(H)    

%%
% When you can |bode| without output arguments, it plots the frequency
% response on the screen. Unless you specify a frequency range to plot,
% |bode| automatically chooses a frequency range based on the system
% dynamics.

%% 
% Calculate the frequency response between 1 and 13 rad/s. 
[mag,phase,w] = bode(H,{1,13}); 
%%
% When you call |bode| with output arguments, the command returns vectors
% |mag| and |phase| containing the magnitude and phase of the frequency
% response. The cell array input |{1,13}| tells |bode| to calculate the
% response at a grid of frequencies between 1 and 13 rad/s. |bode| returns
% the frequency points in the vector |w|.