1X_INIT(1)                    Generic Mapping Tools                   X_INIT(1)
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NAME

6       x_init - Initialization of Cross-Over Data Bases.
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SYNOPSIS

9       x_init -I
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DESCRIPTION

12       The  purpose  of x_init is to create two key files that will be holding
13       all the cross-over information for all the cruises tested. These  files
14       are called xx_base.b and xx_legs.b, and they will contain data for each
15       cross-over and totals for each leg, respectively.  x_init  will  create
16       these  two files in the current directory, and write out the fileheader
17       with a 1 as the next record number in the case of  xx_base.b.  NB!  Any
18       previous  files  with  the  same names in the current directory will be
19       erased, so use with caution.
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21       -I     Must be present form initialization to take effect.
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BEWARE

24       Both files are binary and have fixed record lengths. The formats of the
25       files are as follows:
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27       xx_base.b:
28                   Record length = 40 bytes.
29                   Rec # 1:       fileheader
30                   Rec # 2:       pairheader
31                   Next n recs:        crossover-structure
32                   Rec  #  n+3:        pairheader etc.
33              The  fileheader  is a 40 byte character string where the last 10
34              bytes contains the record number of the last record in the file.
35              The  pairheader is a 40 byte character string which contains the
36              names of the two legs in question and the number of COEs  gener‐
37              ated  between  them.   The  crossover-structure contains all the
38              information for one COE, that is lat, lon, time along leg values
39              of  gravity,  magnetics, and bathymetry at the cross-over point,
40              the heading of track #1, and the heading of track #2.  See  pro‐
41              gram listing for more details on formats. The file is sequential
42              in that new data are appended at the end of the file.
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44       xx_legs.b:
45                   Record length = 204 bytes.
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47              Each record contains the complete information for each leg  that
48              has been checked. The leg-structure contains fields like year of
49              cruise, number of internal/external COEs for gravity, magnetics,
50              and  bathymetry,  their  means  and standard deviations, and the
51              best fitting regression lines, i.e.  the  dc-shifts  and  drift-
52              rates  computed  from  the  time/error  data points. See program
53              listing for complete description of record format.
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SEE ALSO

56       GMT(1), x_system(1)
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REFERENCES

59       Wessel, P. XOVER: A Cross-over Error Detector for Track Data, Computers
60       & Geosciences, 15, 333-346.
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64GMT 4.5.6                         10 Mar 2011                        X_INIT(1)
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