%% The Dirichlet Function
% The function diric computes the Dirichlet function, sometimes called the periodic sinc or aliased sinc function, for an input vector or matrix x. The Dirichlet function is defined by
% D(x)=\cases{{\displaystyle{\sin(Nx/2)}\over{\displaystyle N\sin
% (x/2)}},&$x\ne2\pi k$,\cr(-1)^{k(N-1)},&$x=2\pi k$,\cr}\quad
% k=0,\pm1,\pm2,\pm3,\dots
% where N is a user-specified positive integer. For N odd, the Dirichlet function has a period of 2\pi; for N even, its period is 4\pi. The magnitude of this function is 1/N times the magnitude of the discrete-time Fourier transform of the N-point rectangular window.
% To plot the Dirichlet function between 0 and 4\pi for N=7 and N=8, use

x = linspace(0,4*pi,300);

subplot(2,1,1)
plot(x/pi,diric(x,7))
title('N = 7')

subplot(2,1,2)
plot(x/pi,diric(x,8))
title('N = 8')
xlabel('x / \pi')

% Copyright 2012 The MathWorks, Inc.