# GP migration for a given receiver
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  NX=116      NT=750
  DX=25.0     DT=0.004

  VSURF=1500.0
  FMIN=5.0
  FMAX=55.0
  FREF=35.0
  PARK=0.8
  PARN=0.5
  KAPPA=1.253314137
  MODEL='model2.dat'
  RAYPAR='gpm-rp.out'
  SRC='gpm-src.out'
  CSG='gpm-csg.out'

  gpstep:
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Ray tracing from a given source
  MODEL='mar-mod2.dat' # Model
  SRC='gpm-csg.out'    # File with the coordinates of the initial point
  REC=' '              # No receivers in this example
  DCRT='gb2-crt.dat'   # Numerical parameters for complete ray tracing
  CODE='codep.dat'     # Ray codes
  INIPAR=2             # Geographic-like spherical ray parameters
  RPAR='gb2-crt.dat'   # Ray-parameter domain and control
  WRIT='gpm-writ.dat'  # Names and extent of output files
  CRTLOG='mar-log.out' # Output log file
  crt:                 # Running program crt.for with these data

# Calculating travel times and amplitudes of the incident wave field
#  N1=751  N2=2301  D1=4  D2=4
  N1=151  N2=461  D1=20  D2=20
  NUM='mtt-num.out'  MTT='mtt-tt.out'
  AMP='mtt-apr.out'
  AMP2D3=1.0
  mtt:

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# GP migration
  MODEL='gpm-mod.dat'
  SRC='gpm-src.out'
  DCRT='gpm-crt.dat'
  INIPAR=3
  RPAR='gpm-rp.out'
  crt:

  IXTZU=1
  IXTZD=151
  IXTZL=1
  IXTZR=461

  DT=0.05
  KAPPA=1.0

  GPMSEC='gpms.out'

  gpmig:

  N1=2301  N2=751
  VREF=0   CREF=0.166667   VMIN=-999999000000.0  # VCIRC=1
  GRD='gpms.out'

  grdps: