The method may further include filtering {TAIL ~ the Fourier} transformed data to retain a subset of the Fourier coefficients at each of {HEAD ~ the locations} 
The method may further include filtering { TAIL ~ the Fourier } transformed data to retain a subset of the Fourier coefficients at each of { HEAD ~ the locations }
OTH OTH OTH OTH OTH OTH 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