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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

       gmtvector  reads 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 more tables]. If -fg is 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 -Ci is 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 -Co is set which requests (x, y[,
       z]) Cartesian coordinates.


REQUIRED ARGUMENTS

       None.


OPTIONAL ARGUMENTS

       table  One or more ASCII [or binary, see -bi] file  containing  lon,lat
              [lat,lon  if -:] values in the first 2 columns (if -fg is given)
              or (r, theta), or perhaps (x, y[, z]) if -Ci is  given).  If  no
              file is specified, gmtvector, will read from standard input.

       -Am[conf]|vector
              Specify  a single, primary vector instead of reading tables; see
              tables for possible vector formats. Alternatively, append  m  to
              read  tables  and  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. Append i for
              input only or o for 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].

       -E     Convert input geographic coordinates from geodetic to geocentric
              and  output  geographic coordinates from geocentric to geodetic.
              Ignored unless -fg is in  effect,  and  is  bypassed  if  -C  is
              selected.

       -N     Normalize  the  resultant  vectors prior to reporting the output
              [No normalization]. This only has an effect if -Co is  selected.

       -S[vector]
              Specify  a  single,  secondary  vector in the same format as the
              first vector. Required by operations in -T that 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. Append a for
              average, b for the pole of the two points bisector,  d  for  dot
              product (use D to get angle in degrees between the two vectors),
              paz for the pole to the great circle specified by  input  vector
              and  the  circleas az (no second vector used), s for vector sum,
              rpar for vector rotation (here, par is a single  angle  for  2-D
              Cartesian  data  and  lon/lat/angle  for a 3-D rotation pole and
              angle), R will instead rotate the fixed secondary vector by  the
              rotations implied by the input records, and x for cross-product.
              If -T is not given then no transformation takes place; the  out-
              put is determined by other options such as -A, -C, -E, and -N.

       -V[level] (more a|)
              Select verbosity level [c].

       -bi[ncols][t] (more a|)
              Select native binary input. [Default is 2 or 3 input columns].

       -d[i|o]nodata (more a|)
              Replace  input  columns  that  equal  nodata with NaN and do the
              reverse on output.

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i] (more a|)
              Only accept data records that match the given pattern.

       -f[i|o]colinfo (more a|)
              Specify data types of input and/or output columns.

       -g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u] (more a|)
              Determine data gaps and line breaks.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more a|)
              Skip or produce header record(s).

       -icols[+l][+sscale][+ooffset][,^<i>a|] (more a|)
              Select input columns and transformations (0 is first column).

       -ocols[,a|] (more a|)
              Select output columns (0 is first column).

       -:[i|o] (more a|)
              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 (-bo
       if 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 GMT aspottera supplement.


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
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