fft_desimationintime_butterfly.m

the program is used to find out the FFT using time in decimation and solves problem of dsp fft ,comp

clear all;
close all;
%Give your input here
val=[1 0 1 1 0 1 0 1];
disp('Taken Input values are');
disp(val);
%simple FFT matlab function
%computed with a fast Fourier transform (DFT) algorithm
valy=fft(val);
stem(abs(valy));
title('FFT MATLAB Function');
%simple goertzel matlab function
%Fourier transform (DFT) of specific indices in a vector or matrix
figure;
fy=goertzel(val);
stem(abs(fy));
title('using goertzel MATLAB Function');
 
for k=1:4
    w(k)=exp(-j*2*pi*((k-1)/8));
end
brvsl=bitrevorder(val);
disp('bit reversal values are')
disp(brvsl);
for k=1:4
    g(2*k-1)=brvsl(2*k-1)+brvsl(k*2);
    g(k*2)=brvsl(2*k-1)-brvsl(k*2);
end
for k=1:4
if k>2  k=k+2; end
if(mod(k,2)==1) c=1;else c=3;end;
    h(k)=g(k)+g(k+2)*w(c);
    h(k+2)=g(k)-g(k+2)*w(c);
end
for k=1:4
    y(k)=h(k)+h(k+4)*w(k);
    y(k+4)=h(k)-h(k+4)*w(k);
end
disp(y);
figure;
stem(abs(y));
title('Using fft in time domain (butterfly) ');