splitxyz  -  filter  to  divide  (x,y,z[,distance,heading])  data  into
       (x,y,z) track segments.


       splitxyz [ xyz[dh]file ]  -Ccourse_change  -Dminimum_distance  [  -Aaz-
       imuth/tolerance  ]  [  -Fxy_filter/z_filter  ]  [  -Ggap_distance  ]  [
       -H[nrec] ] [ -M ] [ -Nnamestem ] [ -S ] [  -V  ]  [  -Z  ]  [  -:  ]  [
       -bi[s][n] ] [ -bo[s][n] ] [ -f[i|o]colinfo ]


       splitxyz   reads   a   series   of  (x,y[,z])  records  [or  optionally
       (x,y,z,d,h); see -S option] from standard input  [or  xyz[dh]file]  and
       splits  this  into  separate  lists of (x,y[,z]) series, such that each
       series has a nearly constant azimuth through the x,y plane.  There  are
       options  to  choose only those series which have a certain orientation,
       to set a minimum length for series, and to high- or low-pass filter the
       z  values  and/or  the  x,y values. splitxyz is a useful filter between
       data extraction and pswiggle plotting, and can also be used to divide a
       large  x,y,z  dataset  into segments. The output is always in the ASCII
       format; input may be ASCII or binary (see -b).

              3 (but see -Z) [or 5] column ASCII  file  [or  binary,  see  -b]
              holding  (x,y,z[,d,h])  data  values.  To use (x,y,z,d,h) input,
              sorted so that d  is  non-decreasing,  specify  the  -S  option;
              default expects (x,y,z) only.  If no file is specified, splitxyz
              will read from standard input.

       -C     Terminate a segment when a course change exceeding course_change
              degrees of heading is detected.

       -D     Do  not  write  a segment out unless it is at least minimum_dis-
              tance units long.


       -A     Write out only those segments which  are  within  +/-  tolerance
              degrees of azimuth in heading, measured clockwise from North, [0
              - 360]. [Default writes all acceptable segments,  regardless  of

       -F     Filter  the  z  values and/or the x,y values, assuming these are
              functions of d coordinate.  xy_filter and  z_filter  are  filter
              widths in distance units. If a filter width is zero, the filter-
              ing is not performed. The absolute value of  the  width  is  the
              full  width  of  a  cosine-arch low-pass filter. If the width is
              positive, the data are low-pass filtered; if negative, the  data
              are  high-pass  filtered  by subtracting the low-pass value from
              the observed value. If z_filter is non-zero, the  entire  series
              of  input  z  values is filtered before any segmentation is per-
              formed, so that the only edge effects in the filtering will hap-
              pen  at  the  beginning  and end of the complete data stream. If
              xy_filter is non-zero, the data is first divided  into  segments
              and then the x,y values of each segment are filtered separately.
              This may introduce edge effects at the ends of each segment, but
              prevents  a low-pass x,y filter from rounding off the corners of
              track segments. [Default = no filtering].

       -G     Do not let a segment have a gap exceeding gap_distance; instead,
              split it into two segments. [Default = 10 distance units].

       -H     Input file(s) has Header record(s). Number of header records can
              be changed by editing your  .gmtdefaults4  file.  If  used,  GMT
              default  is  1  header record. Use -Hi if only input data should
              have header records [Default will write out  header  records  if
              the input data have them].  Not used with binary data.

       -M     Use  Map  units. Then x,y are in degrees of longitude, latitude,
              and distances in kilometers. [Default: distances  are  cartesian
              in same units as x,y].

       -N     Create  Named  output  files, writing each segment to a separate
              file in the working directory named namestem.profile#,  where  #
              increases consecutively from 1. [Default writes entire output to
              stdout, separating segments by sub-headings that  start  with  >

       -S     d  and  h  is  supplied. In this case, input contains x,y,z,d,h.
              [Default expects (x,y,z) input, and d,h are computed from  delta
              x, delta y, according to -M option]

       -V     Selects verbose mode, which will send progress reports to stderr
              [Default runs "silently"].

       -Z     Data have x,y only (no z-column).

       -:     Toggles between  (longitude,latitude)  and  (latitude,longitude)
              input  and/or output. [Default is (longitude,latitude)].  Append
              i to select input only or o  to  select  output  only.  [Default
              affects both].

       -bi    Selects  binary input. Append s for single precision [Default is
              double].  Append n for the  number  of  columns  in  the  binary
              [Default is 2, 3, or 5 input columns as set by -S, -Z].

       -bo    Selects binary output. Append s for single precision [Default is
              double].  Append n for the  number  of  columns  in  the  binary

       -f     Special  formatting  of  input  and output columns (time or geo-
              graphical data) Specify i(nput) or  o(utput)  [Default  is  both
              input  and output].  Give one or more columns (or column ranges)
              separated by commas.  Append T (Absolute calendar time), t (time
              relative  to  chosen TIME_EPOCH), x (longitude), y (latitude), g
              (geographic coordinate), or f (floating point) to each column or
              column range item.


       Suppose  you  want  to make a wiggle plot of magnetic anomalies on seg-
       ments oriented approximately east-west from a cruise  called  cag71  in
       the region -R300/315/12/20.  You want to use a 100km low-pass filter to
       smooth the tracks and a 500km high-pass filter to detrend the  magnetic
       anomalies. Try this:

       gmtlist  cag71 -R300/315/12/20 -Fxyzdh | splitxyz -A90/15 -F100/-500 -M
       -D100 -S -V | pswiggle -R300/315/12/20 -Jm0.6  -Ba5f1:.cag71:  -T1  -W3
       -G200 -Z200 >

       MGD-77  users:  For this application we recommend that you extract d, h
       from gmtlist rather than have splitxyz compute them separately.

       Suppose you have been given a binary, double-precision file  containing
       lat,  lon,  gravity values from a survey, and you want to split it into
       profiles named survey.profile# (when gap exceeds 100 km). Try this:

       splitxyz survey.bin -Nsurvey -V -G100 -D100 -: -M -bi3


       gmt(l), gmtlist(l), pswiggle(l)

GMT4.0                            1 Oct 2004                       SPLITXYZ(l)

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