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• FFT

on 20 Nov 2023
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drawframe(1);
function drawframe(f)
N = 32;
y1 = -ones(N,1);
y1(end/2+1:end) = 1;
h = fft(y1);
w = zeros(N, (length(h))/4);
for m0=1:size(w,2)
w(:,m0) = abs(h(m0*2)*2/length(h))*cos(2*pi*(m0*2-1)*(0:N-1)/N+angle(h(m0*2)));
end
N=N*2;
w=repmat(w,2,1);
t=linspace(-1,1,N);
figure(1)
cla
hold on;
m0=f;
grid on;
if m0>6
yy = sum(w(:,1:ceil(m0/6)-1),2) + w(:,ceil(m0/6))*(mod(m0-1,6)+1)/6;
plot3(t, 0*ones(N,1), yy,'Color',[0.8500 0.3250 0.0980],'LineWidth',1)
plot3(t, 0*ones(N,1), w(:,ceil(m0/6)),'Color',[0.8500 0.3250 0.0980 1-(mod(m0-1,6)+1)/6])
else
yy = sum(w(:,1:1),2);
plot3(t, 0*ones(N,1), yy,'Color',[0.8500 0.3250 0.0980],'LineWidth',1)
end
str=cell(5,1);
for m2=1:5
if(ceil(m0/6)+m2 <= size(w,2))
plot3(t, (m2-(mod(m0-1,6)+1)/6)*ones(N,1), w(:,ceil(m0/6)+m2),'color',[0 0.4470 0.7410])
str{m2} = ceil(m0/6)+m2;
end
end
yticks((1:6)-(mod(m0-1,6)+1)/6)
yticklabels(str)
axis([-1 1 0 6 -1.3 1.3])
view([30 30]);
xlabel('time')
ylabel('order')
zlabel('amplitude')
title('FFT')
end