# Two-point ray tracing in a smoothed Marmousi model for zero-offset
# rays, calculation of travel time derivatives with respect to the
# model parameters (B-spline coefficients of P wave slowness field)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Data required
 #chk.pl: "data/mar/" "mar-mod.dat"
 #chk.pl: "data/mar/" "mar-crtz.dat"
 #chk.pl: "data/mar/" "mar-rpaz.dat"
 #chk.pl: "data/mar/" "mar-recz.dat"
 #chk.pl: "crt/"      "codep.dat"
 #chk.pl: "crt/"      "writall.dat"
 #chk.pl: "forms/"    "inv.cal"
 #chk.pl: "forms/"    "append.pl"
 #chk.pl: "data/mar/" "mar-pic.dat"
 #chk.pl: "data/mar/" "mar-fttz.dat"

# Two-point ray tracing
# ~~~~~~~~~~~~~~~~~~~~~
# Initial conditions for rays
  INIDIM=2             # initial surface
  INIPAR=0             # cartesian coordinates
  INIT='mar-rpaz.dat'  # zero-offset rays (exploding reflector)
  RPAR='mar-rpaz.dat'  # ray-parameter domain and control

# Data filenames for CRT
  MODEL='mar-mod.dat'  # Model
  REC='mar-recz.dat'   # Receivers
  DCRT='mar-crtz.dat'  # Numerical parameters for complete ray tracing
  CODE='codep.dat'     # Ray codes (direct P wave)
  WRIT='writall.dat'   # Names and extent of output files with rays
  CRTLOG='mar-log.out' # Output log file of ray tracing

# Ray tracing
  crt:


# Plot of the rays and velocity
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Coarse grid (intervals 40m*80m)
  N1=76  N2=116  D1=40  D2=80  O1=0  O2=0
  MPAR=1  ICB=' '  VEL='mar-v.out'
  grid:
  CAL='inv.cal' GRD1='mar-v.out' GRD2='mar-u.out'
  grdcal:
  VCIRC=.000581818  VREF=.000666667  CREF=0.666667
  HSIZE=7.5   VSIZE=23.
  GRD='mar-u.out' PS='mar-u.ps' SHOWPAGE=0
  grdps:
  LIN='mar-bnd.out'
  bndlin:
  NQ=3 KALL=-1 RAYS='mar-ray.out'
  crtray:
  PICDAT='mar-pic.dat'  PICTURE='mar-ray.ps'
  pictures:
  append.pl:  "mar-u.ps" "mar-ray.ps"


# Writing the file with the initial points of rays
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  SRC=' '  PTS='mar-srcz.out'  KTT=0  KALL=0  KREC=-1  NQ=3
  crtpts:

# Calculating the derivatives of travel times
# with respect to the model B-spline coefficients
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  PTS='mar-recz.dat'  PTS1='mar-srcz.out'
  FTT='mar-fttz.dat'  DIST=1.1  VPOWER=-1
  GM1='gm1.out' #derivatives of the travel times
  invtt: