NAME

       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,  discrepancies  in  gravity/magnet-
       ics/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 an Akima 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.

BEWARE

       The  COEs found are printed out to standard output in ASCII format. The
       first record contains the leg names and their start year, whereas  sub-
       sequent  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 magnet-
       ics, 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  recom-
       mended  that  the  Akima  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. A version of x_over compiled
       for a SUN with FPA board is provided (x_over).

SEE ALSO

       gmt(GMTMANSECTION), x_system(GMTMANSECTION)