Provided by: gmt_4.5.11-1build1_amd64

**NAME**

x_solve_dc_drift- Find Best-fitting D.C.-shift and Drift Estimates

**SYNOPSIS**

x_solve_dc_drift[-Xxbase] [-Llbase] [-Iignorefile] [-S] [-Citeration] [-Mmin_nx] [-Rwest/east/south/north] [-Uuselegsfile] [-V] [-Bbinfile] [-AASCIIfile]

**DESCRIPTION**

x_solve_dc_driftwill read the database files and, by iterating, find the best-fitting regression line to the <time,COE> points for each leg that minimizes the overall standard deviation of the data set in a least squares sense. Finally, correction file(s) are created.-XIndicate an alternate database to read. [Default isxx_base.b].-LIndicate an alternate legbase to read. [Default isxx_legs.b].-IIgnore information for certain legs (that might be bad, etc).-SReset the old d.c.-shift and drift estimates to zero before iterating.-CSpecify how many iterations to do. Default is interactive session.-MSolve for drift only if the leg has more thanmin_nxcross-overs.-ROnly take COEs inside this region into account. [Default is world].-USolve for corrections involving COEs from legs in theuselegsfileonly.-BCreate a binary correction file (which can be read byx_listandgmtlist).-ACreate an ASCII correction table. At least one of-Aand-Bmust be specified.-VSelects verbose mode, which will send progress reports to stderr [Default runs "silently"].

**BEWARE**

The reason for the-Moption is that if the COEs are few, then a stable estimate of the slope may not be obtained (e.g., when most of the COEs occur midway between ports). However, in most cases the bulk of the COEs do occur near the ports so that a drift estimate can be computed. Conventional wisdom recommends plotting the time-series and the computed regression line to see if it makes sense.

**SEE** **ALSO**

GMT(1),x_system(1)

**REFERENCES**

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