clear
close all
N=14;
over=4;
x=cos(2*pi*(0:N-1)/N).^2;
figure(1)
stem((1:over:N*over),x,'filled')
X=fft(x);
Y=zeros(over*N,1);
Y(1:7)=X(1:7);
Y(over*N:-1:over*N-6)=X(N:-1:N-6);
y=ifft(Y*over);
pause
figure(1)
hold on
stem(real(y),'r')
hold off

