foh.m

ipr函数库与仿真实验程序,都是要用到的库函数。

function foh(y,alpha,Ts)
% plot the output of fractional-order hold
% 
% input: y - discrete signal vector as input signal to a fractional 
%            order hold
%        alpha - 0 <= alpha <= 1, hold characteristics
%        Ts = sampling period

%%%%%%%%%%%%%%%%%%%%% foh.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                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

n = length(y);

% first point - need special logic
% it is always assumed that the -1 point is zero

%figure
plot([-1 0]*Ts,[0 0])
hold on 
plot([0 0]*Ts,[0 y(1)])
plot(0,y(1),'o')

yfoh(2) = y(1)+y(1)*alpha;
plot([0 1]*Ts,[y(1) yfoh(2)])
disp('<< press space bar to continue >>'), pause

for ii = 2:n
  plot([ii-1 ii-1]*Ts,[yfoh(ii) y(ii)])
  plot((ii-1)*Ts,y(ii),'o')
  yfoh(ii+1) = y(ii)+(y(ii)-y(ii-1))*alpha;
  plot([ii-1 ii]*Ts,[y(ii) yfoh(ii+1)])
  disp('<< press space bar to continue >>'), pause
end

title('Output of Fractional Order Hold')
xlabel('Time (k*Ts)')
ylabel('Amplitude')

hold off 

%%%%%%%%%%