x_setup(1gmt) [debian man page]

X_SETUP(1gmt)						       Generic Mapping Tools						     X_SETUP(1gmt)

NAME

       x_setup - Determine Pairs of Legs that need Cross-Over Checking

SYNOPSIS

       x_setup [ -Llegfile ] [ -Rwest/east/south/north ]

DESCRIPTION

       x_setup	scans  the gmtindex.b file that contains information on which legs occupy each 1 by 1 degree bin and reports all the pairs of legs
       that may overlap. Each pair is only reported once, even if the two legs involved are found in other bins also.

       -L     Only report pairs where at least one of the legs are present in the legfile.

       -R     The region of interest.  [Default is world]

BEWARE

       The -L option is useful when one wants to check out a handful of new cruises. Obviously we only need to compute COEs  for  the  pairs  that
       involve one or two of the new cruises, since all the other combinations have already been done.

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_SETUP(1gmt)

X_INIT(1gmt)						       Generic Mapping Tools						      X_INIT(1gmt)

NAME

       x_init - Initialization of Cross-Over Data Bases.

SYNOPSIS

       x_init -I

DESCRIPTION

       The  purpose  of  x_init  is  to create two key files that will be holding all the cross-over information for all the cruises tested. These
       files are called xx_base.b and xx_legs.b, and they will contain data for each cross-over and totals for	each  leg,  respectively.   x_init
       will  create  these  two  files	in  the  current directory, and write out the fileheader with a 1 as the next record number in the case of
       xx_base.b. NB! Any previous files with the same names in the current directory will be erased, so use with caution.

       -I     Must be present form initialization to take effect.

BEWARE

       Both files are binary and have fixed record lengths. The formats of the files are as follows:

       xx_base.b:
		   Record length = 40 bytes.
		   Rec # 1:	  fileheader
		   Rec # 2:	  pairheader
		   Next n recs:        crossover-structure
		   Rec	#  n+3:        pairheader etc.
	      The fileheader is a 40 byte character string where the last 10 bytes contains the record number of the last record in the file.  The
	      pairheader  is  a  40  byte  character  string which contains the names of the two legs in question and the number of COEs generated
	      between them.  The crossover-structure contains all the information for one COE, that is lat, lon, time along leg values of gravity,
	      magnetics,  and  bathymetry  at  the cross-over point, the heading of track #1, and the heading of track #2. See program listing for
	      more details on formats. The file is sequential in that new data are appended at the end of the file.

       xx_legs.b:
		   Record length = 204 bytes.

	      Each record contains the complete information for each leg that has been checked. The leg-structure contains  fields  like  year	of
	      cruise,  number  of internal/external COEs for gravity, magnetics, and bathymetry, their means and standard deviations, and the best
	      fitting regression lines, i.e. the dc-shifts and drift-rates computed from the time/error data points. See program listing for  com-
	      plete description of record format.

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_INIT(1gmt)