Page 188 - Applied Numerical Methods Using MATLAB

PROBLEMS 177
by using the MATLAB built-in routine “fft()”. You can start with the
incomplete MATLAB program “do_RDFT.m”below.

%do_RDFT
clear, clf
N = 128; k = [0:N - 1];
x = zeros(1,N); %initialize the data block
Xr = zeros(1,N); % and its DFT
for m = 0:N
xN = rand; %new data
Xr = (Xr + xN - x(1)).*???????????????? %RDFT formula (P3.20.5)
x = [x(2:N) xN];
end
dif = norm(Xr-fft(x)) %difference between RDFT and FFT