x_over

       x_over - Find and compute Cross-Over Errors

SYNOPSIS

       x_over  leg_1  [  leg_2  ]  [  -A ] [ -C ] [ -L ] [ -V ] [
       -Wtimegap ] [ -Gfact ] [ -Mfact ] [ -Tfact ] [ -Nnp_int ]

DESCRIPTION

       x_over is used to inspect  two  cruises  to  see  if  they
       intersect, and if so report the time, position, discrepan­
       cies in  gravity/magnetics/bathymetry,  heading  for  each
       track  segment,  and the average values of the geophysical
       observables at the cross-over point. The names of the legs
       are  passed  on the command line. If they are identical or
       only one name is passed, then x_over  looks  for  internal
       cross-overs. The optional parameters are:

       -A     Use  Akima's  spline to interpolate the geophysical
              field at the cross-over point.'

       -C     Use a Natural Cubic spline function instead.

       -L     Use a linear interpolant [Default].

       -W     Do not compute cross-overs if the 2 nearest  points
              are more than timegap minutes apart.

       -G     Scale  gravity  by  fact [Default is 0.1 since gmt-
              files store gravity in g.u.]

       -M     Scale magnetic anomaly by fact [1.0].

       -T     Scale bathymetry by fact [1.0].

       -N     Specify how many points to use in the interpolation
              [Default is 6].

       -V     Verbose,  report the number of cross-overs for this
              pair of legs.

The COEs found are printed out to standard output in ASCII for­

       mat. The first record contains the
       leg names and their start year, whereas subsequent records
       have the data for each COE encountered. The fields written
       out  are  lat,  lon, time along track #1, time along track
       #2, x_gravity, x_magnetics, x_bathymetry, average gravity,
       average magnetics, average bathymetry, heading along track
       #1, and heading along track #2. Sign convention:  If  lega
       and  legb  are  passed  on  the command line, then the COE
       value is Value (lega) - Value (legb).  It  is  recommended
       that  the  Akima's  spline  is used instead of the natural
       cubic spline, since it is less sensitive to' outliers that
       tend  to introduce wild oscillations in the interpolation.

SEE ALSO

       gmt(l), x_system(l)

REFERENCES

       Wessel,  P.  XOVER:  A Cross-over Error Detector for Track
       Data, Computers & Geosciences, 15, 333-346.