# Calculating optimum initial parameters of Gaussian beams
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Compute ray parameters, source and receiver coordinates
  MODEL='mar-mod.dat' GPSTEP='mgbstep.ini'
  SRC='mgb-src.out'   REC='mgb-rec.out'   RPAR='mgb-rpa.out' 
  X1SRC=8.   X2SRC=0. X3SRC=0.
  X1REC=12.  X2REC=0. X3REC=0.
  OSRC=3000. DSRC=25. OXRINI=425.  KOLPAR=1
  gprpar:

# Ray tracing for source points
  REC=' '
  DCRT='mgb-crt.dat'  CODE='codep.dat'    INIPAR=2
  RPAR='mgb-crt.dat'  WRIT='writall.dat'  CRTLOG='agp-log2.out'
  crt:

# Calculating travel times at given gridpoints for source
  N1=121 N2=369  D1=25. D2=25.
  NUM='mtt-num.out'  MTT='mtt-tt.out'
  mtt:
  echo.pl: "44649*1" ">mtt-ap.out"    # Unit amplitudes for weighting

# Ray tracing for receiver points
  SRC='mgb-rec.out'  RPAR='mgb-rpa.out'  WRIT='mgp-wri.dat'
  crt:

# Calculate optimum initial parameters of Gaussian beams
  CRTOUT=' ' AMP='mtt-ap.out' 
  FGBR22='r0s.out' FGBY22='y0s.out' FSIGMA='sigmar.out' FTAU='tau.out'
  NTR=26  NP=48
  gbopt: