x_list(1gmt) [debian man page]

X_LIST(1gmt)						       Generic Mapping Tools						      X_LIST(1gmt)

NAME

       x_list - Extract Cross-Over Information from the Data Base.

SYNOPSIS

       x_list [ leg1 ] [ leg2 ] [ -dataflags ] [ -Rwest/east/south/north ] [ -Xxbase ] [ -H ] [ -I ] [ -V ] [ -Ccorrfile ] [ -Zignorefile ]

DESCRIPTION

       x_list  will  allow  the  user to extract information from the xx_base.b and xx_legs.b files.  Several options can be passed on the command
       line in order to specify which parameters to extract. They are:

       leg1 leg2
	      If two legs are specified, the cross-overs they have in common are returned.  If one leg is specified, all the external  cross-overs
	      involving  this  leg  are  returned, OR only its internal cross-overs if -I is selected.	If no legs are given, all the external (or
	      internal with -I) cross-overs are returned.  This program is useful if one wants to look at, say, gravity COEs versus time from port
	      for a particular leg, etc.

       dataflags
	      This is a string of any combination of the following:
		   l means list both legnames.
		   t means list time.
		   x means list longitude.
		   y means list latitude.
		   g means list gravity COEs.
		   m means list magnetics COEs.
		   b means list bathymetry COEs.
		   G means list average gravity at cross-over.
		   M means list average magnetic anomaly at cross-over.
		   B means list average bathymetry at cross-over.
		   h means list heading of ship at cross-over.
	      The  components  are  written out in the order they appear in dataflags. The default output is -txygmbGMBhl.  When internal COEs are
	      desired, the time reported is the elapsed time since the ship first occupied the cross-over point. For external COEs the time  means
	      time from the start of the year in seconds.

       -R     Only return cross-overs inside the specified region west, east, south, and north.  [Default is world].

       -X     Indicate alternate xx_base.b file.

       -H     Issue one header record on output.

       -I     Report on internal COEs [Default is external COEs].

       -C     Apply  cross-over  correction to the data (i.e. reports the cross-over value after the best-fitting corrections have been applied to
	      both legs). If no corrfile is given, the default correction file is assumed.

       -Z     Ignore those legs that appear in the ignorefile.

       -V     Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].

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 4.5.7							    15 Jul 2011 						      X_LIST(1gmt)

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X_OVER(1gmt)						       Generic Mapping Tools						      X_OVER(1gmt)

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/ba-
       thymetry, 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  rec-
       ommended  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 4.5.7							    15 Jul 2011 						      X_OVER(1gmt)

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x_list(1gmt) [debian man page]

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