function maxabsdiff=tailscrap()% test code for circular convolution with the scrapped portion % at the tail of the buffer, rather than the front%% The idea is to rotate the zero-padded h (impulse response) buffer% to the left nh-1 samples, rotating the junk samples as well.% This could be very handy in avoiding buffer copies during fast filtering.nh=10;nfft=256;h=rand(1,nh);x=rand(1,nfft);hpad=[ h(nh) zeros(1,nfft-nh) h(1:nh-1) ]; % baseline comparisony1 = filter(h,1,x);y1_notrans = y1(nh:nfft);% fast convolutiony2 = ifft( fft(hpad) .* fft(x) );y2_notrans=y2(1:nfft-nh+1);maxabsdiff = max(abs(y2_notrans - y1_notrans))end