sippi_setup_gpr_fd: Inversion of full waveform GPR data.
 
 
  /REF/See also
     https://sites.google.com/site/kscordua/downloads/tomographic-full-waveform-inversion
     Ernst, J. R., H. Maurer, A. G. Green, and K. Holliger, 2007, Full-waveform inversion of crosshole radar data based on 2-D finite-difference time domain solutions of Maxwell�s equations: IEEE Transactions on Geoscience and Remote Sensing, 45, 2807�2828.
     Cordua, K. S., T. M. Hansen, and K. Mosegaard, 2012. Monte Carlo full waveform inversion of crosshole GPR data using multiple-point geostatistical a priori information. Geophysics, 77(2), H19 � H31.
 
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