gmtvector(1) GMT gmtvector(1)

## NAME

gmtvector - Basic manipulation of Cartesian vectors

## SYNOPSIS

gmtvector[tables] [-Am[conf]|vector] [-C[i|o] ] [-E] [-N] [-Svector] [-Ta|d|D|paz|r[arg|R|s|x] ] [-V[level] ] [-bbinary ] [-dnodata ] [-eregexp ] [-fflags ] [-ggaps ] [-hheaders ] [-iflags ] [-oflags ] [-:[i|o] ]Note:No space is allowed between the option flag and the associated arguments.

## DESCRIPTION

gmtvectorreads either (x, y), (x, y, z), (r, theta) or (lon, lat) [or (lat,lon); see-:] coordinates from the first 2-3 columns on standard input [or one or moretables]. If-fgis selected and only two items are read (i.e., lon, lat) then these coordinates are converted to Cartesian three-vectors on the unit sphere. Otherwise we expect (r, theta) unless-Ciis in effect. If no file is found we expect a single vector to be given as argument to-A; this argument will also be inter- preted as an x/y[/z], lon/lat, or r/theta vector. The input vectors (or the one provided via-A) are denoted the prime vector(s). Several stan- dard vector operations (angle between vectors, cross products, vector sums, and vector rotations) can be selected; most require a single sec- ond vector, provided via-S. The output vectors will be converted back to (lon, lat) or (r, theta) unless-Cois set which requests (x, y[, z]) Cartesian coordinates.

## REQUIRED ARGUMENTS

None.

## OPTIONAL ARGUMENTS

tableOne or more ASCII [or binary, see-bi] file containing lon,lat [lat,lon if-:] values in the first 2 columns (if-fgis given) or (r, theta), or perhaps (x, y[, z]) if-Ciis given). If no file is specified,gmtvector, will read from standard input.-Am[conf]|vectorSpecify a single, primary vector instead of readingtables; seetablesfor possible vector formats. Alternatively, appendmto readtablesand set the single, primary vector to be the mean resultant vector first. We also compute the confidence ellipse for the mean vector (azimuth of major axis, major axis, and minor axis; for geographic data the axes will be reported in km). You may optionally append the confidence level in percent [95]. These three parameters are reported in the final three output columns.-C[i|o] Select Cartesian coordinates on input and output. Appendifor input only orofor output only; otherwise both input and output will be assumed to be Cartesian [Default is polar r/theta for 2-D data and geographic lon/lat for 3-D].-EConvert input geographic coordinates from geodetic to geocentric and output geographic coordinates from geocentric to geodetic. Ignored unless-fgis in effect, and is bypassed if-Cis selected.-NNormalize the resultant vectors prior to reporting the output [No normalization]. This only has an effect if-Cois selected.-S[vector] Specify a single, secondary vector in the same format as the first vector. Required by operations in-Tthat need two vectors (average, bisector, dot product, cross product, and sum).-Ta|d|D|paz|s|r[arg|R|x] Specify the vector transformation of interest. Appendafor average,bfor the pole of the two points bisector,dfor dot product (useDto get angle in degrees between the two vectors),pazfor the pole to the great circle specified by input vector and the circleasaz(no second vector used),sfor vector sum,rparfor vector rotation (here,paris a single angle for 2-D Cartesian data andlon/lat/anglefor a 3-D rotation pole and angle),Rwill instead rotate the fixed secondary vector by the rotations implied by the input records, andxfor cross-product. If-Tis not given then no transformation takes place; the out- put is determined by other options such as-A,-C,-E, and-N.-V[level] (morea|) Select verbosity level [c].-bi[ncols][t] (morea|) Select native binary input. [Default is 2 or 3 input columns].-d[i|o]nodata(morea|) Replace input columns that equalnodatawith NaN and do the reverse on output.-e[~]^<i>apattern^<i>a|-e[~]/regexp/[i] (morea|) Only accept data records that match the given pattern.-f[i|o]colinfo(morea|) Specify data types of input and/or output columns.-g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u] (morea|) Determine data gaps and line breaks.-h[i|o][n][+c][+d][+rremark][+rtitle] (morea|) Skip or produce header record(s).-icols[+l][+sscale][+ooffset][,^<i>a|] (morea|) Select input columns and transformations (0 is first column).-ocols[,a|] (morea|) Select output columns (0 is first column).-:[i|o] (morea|) Swap 1st and 2nd column on input and/or output.-^or just-Print a short message about the syntax of the command, then exits (NOTE: on Windows just use-).-+or just+Print an extensive usage (help) message, including the explana- tion of any module-specific option (but not the GMT common options), then exits.-?or no arguments Print a complete usage (help) message, including the explanation of all options, then exits.

## ASCII FORMAT PRECISION

The ASCII output formats of numerical data are controlled by parameters in your gmt.conf file. Longitude and latitude are formatted according to FORMAT_GEO_OUT, absolute time is under the control of FOR- MAT_DATE_OUT and FORMAT_CLOCK_OUT, whereas general floating point val- ues are formatted according to FORMAT_FLOAT_OUT. Be aware that the for- mat in effect can lead to loss of precision in ASCII output, which can lead to various problems downstream. If you find the output is not written with enough precision, consider switching to binary output (-boif available) or specify more decimals using the FORMAT_FLOAT_OUT set- ting.

## EXAMPLES

Suppose you have a file with lon, lat called points.txt. You want to compute the spherical angle between each of these points and the loca- tion 133/34. Try gmt vector points.txt -S133/34 -TD -fg > angles.txt To rotate the same points 35 degrees around a pole at 133/34, and out- put Cartesian 3-D vectors, use gmt vector points.txt -Tr133/34/35 -Co -fg > reconstructed.txt To rotate the point 65/33 by all rotations given in file rots.txt, use gmt vector rots.txt -TR -S64/33 -fg > reconstructed.txt To compute the cross-product between the two Cartesian vectors 0.5/1/2 and 1/0/0.4, and normalizing the result, try gmt vector -A0.5/1/2 -Tx -S1/0/0.4 -N -C > cross.txt To rotate the 2-D vector, given in polar form as r = 2 and theta = 35, by an angle of 120, try gmt vector -A2/35 -Tr120 > rotated.txt To find the mid-point along the great circle connecting the points 123/35 and -155/-30, use gmt vector -A123/35 -S-155/-30 -Ta -fg > midpoint.txt To find the mean location of the geographical points listed in points.txt, with its 99% confidence ellipse, use gmt vector points.txt -Am99 -fg > centroid.txt To find the pole corresponding to the great circle that goes through the point -30/60 at an azimuth of 105 degrees, use gmt vector -A-30/60 -Tp105 -fg > pole.txt

## ROTATIONS

For more advanced 3-D rotations as used in plate tectonic reconstruc- tions, see the GMTaspotterasupplement.

## SEE ALSO

gmt(1),project(1),mapproject(1)

## COPYRIGHT

2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe 5.4.2 Jun 24, 2017 gmtvector(1)

gmt5 5.4.2 - Generated Wed Jun 28 18:04:18 CDT 2017