function k0 = nufft_offset(om, J, K)%function k0 = nufft_offset(om, J, K)% offset for NUFFT%	om [...]	omega in [-pi, pi) (not essential!)%	J		# of neighbors used%	K		FFT size% out:%	k0 [...]	prepare to use mod(k0 + [1:J], K) + 1%	the extra "+1" up here -^ is because matlab counts from 1, not 0% Copyright 2000-1-9, Jeff Fessler, The University of Michiganif nargin < 3, help(mfilename), error args, endif mod(J,2)	% odd J	k0 = round(om / (2*pi/K)) - (J+1)/2;else		% even J	k0 = floor(om / (2*pi/K)) - J/2;end