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 comparison

y1 = filter(h,1,x);

y1_notrans = y1(nh:nfft);

% fast convolution

y2 = ifft( fft(hpad) .* fft(x) );

y2_notrans=y2(1:nfft-nh+1);

maxabsdiff = max(abs(y2_notrans - y1_notrans))

end