x_init(1) Initialization of Cross-Over Data Bases.


x_init -I


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.
Must be present form initialization to take effect.


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


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