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_drift will 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.
-X Indicate an alternate database to read. [Default is xx_base.b].
-L Indicate an alternate legbase to read. [Default is xx_legs.b].
-I Ignore information for certain legs (that might be bad etc).
-S Reset the old d.c.-shift and drift estimates to zero before
iterating.
-C Specify how many iterations to do. Default is interactive ses-
sion.
-M Solve for drift only if the leg has more than min_nx cross-
overs.
-R Only take COEs inside this region into account. [Default is
world].
-U Solve for corrections involving COEs from legs in the uselegs-
file only.
-B Create a binary correction file (which can be read by xlist and
gmtlist).
-A Create an ASCII correction table. At least one of -A and -B must
be specified.
-V Operate in verbose mode.
The reason for the -M option is that if the COEs are few, then a stable esti-
mate 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(GMTMANSECTION), x_system(GMTMANSECTION)
REFERENCES
Wessel, P. XOVER: A Cross-over Error Detector for Track Data, Computers
& Geosciences, 15, 333-346.
1 Jan 2004 x_solve_dc_drift(l)
Man(1) output converted with
man2html