<span class="comment">% find the Hilbert transform</span>
alphatmp = fft(alpha);
alphatmp(floor(m/2)+1:m) = -alphatmp(floor(m/2)+1:m);
alphatmp(1) = 0;
alphatmp(floor(m/2)+1) = 0;
phi = real(ifft(j*alphatmp));

<span class="comment">% now retrieve the original sampling</span>
index  = find(rem([0:m-1],mult_factor)==0);
alpha1 = alpha(index);
phi1   = phi(index);

<span class="comment">% compute the impulse response (inverse Fourier transform)</span>
h = real(ifft(exp(alpha1+j*phi1),n));
</pre>
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