Synopsis
		sfspitzbl < in.rsf > out.rsf order=3 ntraces=1 f1=0.0 f2=1.0 verb=n norm=y

based on Seismic trace interpolation in the F-X domain
S.Spitz Geophysics 56, 785(1991).
This implementation is for bandlimited [f1 f2] signals

Parameters
		float f1=0.0 lower frequency in band limited signal >= 0.0   float f2=1.0 higher frequency in band limited signal <= 1.0 (normalized nyquist)   bool norm=y [y/n] normalization flag   int ntraces=1 number of traces to be interpolated   int order=3 linear PEF order   bool verb=n [y/n] verbosity flag