{TAIL ~ The Fourier transformed data} is filtered by retaining a subset of the Fourier coefficients at each of {HEAD ~ the locations} 
{ TAIL ~ The Fourier transformed data } is filtered by retaining a subset of the Fourier coefficients at each of { HEAD ~ the locations }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD