DragonFly On-Line Manual Pages

X_OVER(1)                    Generic Mapping Tools                   X_OVER(1)

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/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 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     Selects verbose mode, which will send progress reports to stderr
              [Default runs "silently"].  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
       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 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(1), x_system(1)

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

GMT 4.5.14                        1 Nov 2015                         X_OVER(1)