x2sys_cross - Calculate crossovers between track data files


gmt x2sys_cross track(s) -TTAG [ -Acombi.lis ] [ -C[runtimes] ] [ -D[S|N] ] [ -Il|a|c ] [ -Qe|i ] [ -Sl|u|hspeed ] [ -V[level] ] [ -Wsize ] [ -Z ] [ -bobinary ] [ -donodata ] [ --PAR=value ]




Required Arguments

Specify the x2sys TAG which identifies the attributes of this data type.

Optional Arguments

Control how geographic coordinates are handled (Cartesian data are unaffected). By default, we determine if the data are closer to one pole than the other, and then we use a cylindrical polar conversion to avoid problems with longitude jumps. You can turn this off entirely with -D and then the calculations uses the original data (we have protections against longitude jumps). However, you can force the selection of the pole for the projection by appending S or N for the south or north pole, respectively. The conversion is used because the algorithm used to find crossovers are inherently a Cartesian algorithm that can run into trouble with data that has large longitudinal range at higher latitudes.


l Linear interpolation [Default].

a Akima spline interpolation.

c Cubic spline interpolation.

west, east, south, and north specify the region of interest, and you may specify them in decimal degrees or in [±]dd:mm[:ss.xxx][W|E|S|N] format Append +r if lower left and upper right map coordinates are given instead of w/e/s/n. The two shorthands -Rg and -Rd stand for global domain (0/360 and -180/+180 in longitude respectively, with -90/+90 in latitude). Set geographic regions by specifying ISO country codes from the Digital Chart of the World using -Rcode1,code2,…[+r|R[incs]] instead: Append one or more comma-separated countries using the 2-character ISO 3166-1 alpha-2 convention. To select a state of a country (if available), append .state, e.g, US.TX for Texas. To specify a whole continent, prepend = to any of the continent codes AF (Africa), AN (Antarctica), AS (Asia), EU (Europe), OC (Oceania), NA (North America), or SA (South America). Use +r to modify the bounding box coordinates from the polygon(s): Append inc, xinc/yinc, or winc/einc/sinc/ninc to adjust the region to be a multiple of these steps [no adjustment]. Alternatively, use +R to extend the region outward by adding these increments instead [no extension]. Alternatively for grid creation, give Rcodelon/lat/nx/ny, where code is a 2-character combination of L, C, R (for left, center, or right) and T, M, B for top, middle, or bottom. e.g., BL for lower left. This indicates which point on a rectangular region the lon/lat coordinate refers to, and the grid dimensions nx and ny with grid spacings via -I is used to create the corresponding region. Alternatively, specify the name of an existing grid file and the -R settings (and grid spacing, if applicable) are copied from the grid. Appending +uunit expects projected (Cartesian) coordinates compatible with chosen -J and we inversely project to determine actual rectangular geographic region. For perspective view (-p), optionally append /zmin/zmax. In case of perspective view (-p), a z-range (zmin, zmax) can be appended to indicate the third dimension. This needs to be done only when using the -Jz option, not when using only the -p option. In the latter case a perspective view of the plane is plotted, with no third dimension. For Cartesian data just give xmin/xmax/ymin/ymax. This option limits the COEs to those that fall inside the specified domain.


-Sl sets lower speed [Default is 0].

-Su sets upper speed [Default is Infinity].


-V[level] (more …)
Select verbosity level [c].
-bo[ncols][type] (more …)
Select native binary output.
-donodata (more …)
Replace output columns that equal NaN with nodata.
-^ or just -
-+ or just +
-? or no arguments



Sign Convention


Precision And Format

The output format of individual columns are controlled by FORMAT_FLOAT_OUT except for geographic coordinates (FORMAT_GEO_OUT) and absolute calendar time (FORMAT_DATE_OUT, FORMAT_CLOCK_OUT). Make sure these are set to give you enough significant digits to achieve the desired precision.



gmt x2sys_cross c2104.gmt -TGMT > c2104.txt


gmt x2sys_cross A13232.mgd77 A99938.mgd77 -Qe -TMGD77 > crossovers.txt


