clear all
close
clc
figure;
x=[1,1,1];
n=1000;
w=[0:n-1]*2*pi/n;
X=fft(x,n);
subplot(2,1,1);
plot(w,abs(X));
hold on ;
N=2;
wn=[0:N-1]*2*pi/N;
Xn=[];
for i=0:N-1
Xn=[Xn,X(1+fix(i*n/N))];
end
stem(real(wn),abs(Xn));
x1=ifft(Xn);
subplot(2,1,2);
stem([0:N-1],x1);
figure;
x=[1,1,1];
n=1000;
w=[0:n-1]*2*pi/n;
X=fft(x,n);
subplot(2,1,1);
plot(w,abs(X));
hold on ;
N=3;
wn=[0:N-1]*2*pi/N;
Xn=[];
for i=0:N-1
Xn=[Xn,X(1+fix(i*n/N))];
end
stem(wn,abs(Xn));
x1=ifft(Xn);
subplot(2,1,2);
stem([0:N-1],real(x1));
figure;
x=[1,1,1];
n=1000;
w=[0:n-1]*2*pi/n;
X=fft(x,n);
subplot(2,1,1);
plot(w,abs(X));
hold on ;
N=10;
wn=[0:N-1]*2*pi/N;
Xn=[];
for i=0:N-1
Xn=[Xn,X(1+fix(i*n/N))];
end
stem(wn,abs(Xn));
x1=ifft(Xn);
subplot(2,1,2);
stem([0:N-1],x1);
