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gmt(1)                                GMT                               gmt(1)




NAME

       gmt  -  The  Generic Mapping Tools data processing and display software
       package


INTRODUCTION

       GMT is a collection of public-domain Unix  tools  that  allows  you  to
       manipulate x,y and x,y,z data sets (filtering, trend fitting, gridding,
       projecting, etc.) and produce  PostScript  illustrations  ranging  from
       simple  x-y  plots,  via contour maps, to artificially illuminated sur-
       faces and 3-D perspective views in black/white or full  color.  Linear,
       log10, and power scaling is supported in addition to over 30 common map
       projections. The processing and display routines within  GMT  are  com-
       pletely general and will handle any (x,y) or (x,y,z) data as input.


SYNOPSIS

       gmt is the main program that can start any of the modules:

       gmt module module-options

       where module is the name of a GMT module and the options are those that
       pertain to that particular module.  A  few  special  modules  are  also
       available:

       gmt clear items

       while  delete  the useras history.  Choose between history (deletes the
       gmt.history file in the current directory), conf (deletes the  gmt.conf
       file  in the current directory), cache (deletes the useras cache direc-
       tory and all of its content), or all (does all of the above).

       If no module is given then several other options are available:

       --help List and description of GMT modules.

       --show-cores
              Show number of available cores.

       --show-bindir
              Show directory of executables and exit.

       --show-datadir
              Show data directory/ies and exit.

       --show-modules
              List module names on stdout and exit.

       --show-plugindir
              Show plugin directory and exit.

       --show-sharedir
              Show share directory and exit.

       --version
              Print version and exit.

       =      Check if that module exist and if so the program will exit  with
              status of 0; otherwise the status of exit will be non-zero.


COMMAND-LINE COMPLETION

       GMT  provides  basic command-line completion (tab completion) for bash.
       The completion rules are either installed in /etc/bash_completion.d/gmt
       or  <prefix>/share/tools/gmt_completion.bash.  Depending on the distri-
       bution, you may still need to  source  the  gmt  completion  file  from
       ~/.bash_completion or ~/.bashrc.  For more information see Section com-
       mand-line-completion in the CookBook.


GMT OVERVIEW

       The following is a summary of all the programs supplied with GMT and  a
       very  short  description  of  their purpose. Detailed information about
       each program can be found in the separate manual pages.

                      +---------------+-----------------------+
                      |blockmean      |                       |
                      +---------------+-----------------------+
                      |blockmedian    |                       |
                      +---------------+-----------------------+
                      |blockmode      |                       |
                      +---------------+-----------------------+
                      |filter1d       |                       |
                      +---------------+-----------------------+
                      |fitcircle      |                       |
                      +---------------+-----------------------+
                      |gmt2kml        |                       |
                      +---------------+-----------------------+
                      |gmtconnect     |                       |
                      +---------------+-----------------------+
                      |gmtconvert     |                       |
                      +---------------+-----------------------+
                      |gmtdefaults    |                       |
                      +---------------+-----------------------+
                      |gmtget         |                       |
                      +---------------+-----------------------+
                      |gmtinfo        |                       |
                      +---------------+-----------------------+
                      |gmtmath        |                       |
                      +---------------+-----------------------+
                      |gmtselect      |                       |
                      +---------------+-----------------------+
                      |gmtset         |                       |
                      +---------------+-----------------------+
                      |gmtspatial     |                       |
                      +---------------+-----------------------+
                      |gmtsimplify    |                       |
                      +---------------+-----------------------+
                      |gmtvector      |                       |
                      +---------------+-----------------------+
                      |gmtwhich       |                       |
                      +---------------+-----------------------+
                      |grd2cpt        |                       |
                      +---------------+-----------------------+
                      |grd2rgb        |                       |
                      +---------------+-----------------------+
                      |grd2xyz        |                       |
                      +---------------+-----------------------+
                      |grdblend       |                       |
                      +---------------+-----------------------+
                      |grdclip        |                       |
                      +---------------+-----------------------+
                      |grdcontour     |                       |
                      +---------------+-----------------------+
                      |grdconvert     |                       |
                      +---------------+-----------------------+
                      |grdcut         |                       |
                      +---------------+-----------------------+
                      |grdedit        |                       |
                      +---------------+-----------------------+


                      |grdfft         |                       |
                      +---------------+-----------------------+
                      |grdfilter      |                       |
                      +---------------+-----------------------+
                      |grdgradient    |                       |
                      +---------------+-----------------------+
                      |grdhisteq      |                       |
                      +---------------+-----------------------+
                      |grdimage       |                       |
                      +---------------+-----------------------+
                      |grdinfo        |                       |
                      +---------------+-----------------------+
                      |grdlandmask    |                       |
                      +---------------+-----------------------+
                      |grdmask        |                       |
                      +---------------+-----------------------+
                      |grdmath        |                       |
                      +---------------+-----------------------+
                      |grdpaste       |                       |
                      +---------------+-----------------------+
                      |grdproject     |                       |
                      +---------------+-----------------------+
                      |grdraster      |                       |
                      +---------------+-----------------------+
                      |grdsample      |                       |
                      +---------------+-----------------------+
                      |grdtrack       |                       |
                      +---------------+-----------------------+
                      |grdtrend       |                       |
                      +---------------+-----------------------+
                      |grdvector      |                       |
                      +---------------+-----------------------+
                      |grdview        |                       |
                      +---------------+-----------------------+
                      |grdvolume      |                       |
                      +---------------+-----------------------+
                      |greenspline    |                       |
                      +---------------+-----------------------+
                      |kml2gmt        |                       |
                      +---------------+-----------------------+
                      |makecpt        |                       |
                      +---------------+-----------------------+
                      |mapproject     |                       |
                      +---------------+-----------------------+
                      |nearneighbor   |                       |
                      +---------------+-----------------------+
                      |project        |                       |
                      +---------------+-----------------------+
                      |psbasemap      |                       |
                      +---------------+-----------------------+
                      |psclip         |                       |
                      +---------------+-----------------------+
                      |pscoast        |                       |
                      +---------------+-----------------------+
                      |pscontour      |                       |
                      +---------------+-----------------------+
                      |psconvert      |                       |
                      +---------------+-----------------------+
                      |pshistogram    |                       |
                      +---------------+-----------------------+
                      |psimage        |                       |
                      +---------------+-----------------------+
                      |pslegend       |                       |
                      +---------------+-----------------------+


                      |psmask         |                       |
                      +---------------+-----------------------+
                      |psrose         |                       |
                      +---------------+-----------------------+
                      |psscale        |                       |
                      +---------------+-----------------------+
                      |pstext         |                       |
                      +---------------+-----------------------+
                      |pswiggle       |                       |
                      +---------------+-----------------------+
                      |psxy           |                       |
                      +---------------+-----------------------+
                      |psxyz          |                       |
                      +---------------+-----------------------+
                      |sample1d       |                       |
                      +---------------+-----------------------+
                      |spectrum1d     |                       |
                      +---------------+-----------------------+
                      |splitxyz       |                       |
                      +---------------+-----------------------+
                      |surface        |                       |
                      +---------------+-----------------------+
                      |trend1d        |                       |
                      +---------------+-----------------------+
                      |trend2d        |                       |
                      +---------------+-----------------------+
                      |triangulate    |                       |
                      +---------------+-----------------------+
                      |xyz2grd        |                       |
                      +---------------+-----------------------+
                      |               | Supplement gshhg:     |
                      +---------------+-----------------------+
                      |gshhg          |                       |
                      +---------------+-----------------------+
                      |               | Supplement img:       |
                      +---------------+-----------------------+
                      |img2grd        |                       |
                      +---------------+-----------------------+
                      |               | Supplement meca:      |
                      +---------------+-----------------------+
                      |pscoupe        |                       |
                      +---------------+-----------------------+
                      |psmeca         |                       |
                      +---------------+-----------------------+
                      |pspolar        |                       |
                      +---------------+-----------------------+
                      |psvelo         |                       |
                      +---------------+-----------------------+
                      |pssac          |                       |
                      +---------------+-----------------------+
                      |               | Supplement mgd77:     |
                      +---------------+-----------------------+
                      |mgd77convert   |                       |
                      +---------------+-----------------------+
                      |mgd77header    |                       |
                      +---------------+-----------------------+
                      |mgd77info      |                       |
                      +---------------+-----------------------+
                      |mgd77list      |                       |
                      +---------------+-----------------------+
                      |mgd77magref    |                       |
                      +---------------+-----------------------+
                      |mgd77manage    |                       |
                      +---------------+-----------------------+


                      |mgd77path      |                       |
                      +---------------+-----------------------+
                      |mgd77sniffer   |                       |
                      +---------------+-----------------------+
                      |mgd77track     |                       |
                      +---------------+-----------------------+
                      |               | Supplement potential: |
                      +---------------+-----------------------+
                      |gmtgravmag3d   |                       |
                      +---------------+-----------------------+
                      |gmtflexure     |                       |
                      +---------------+-----------------------+
                      |gpsgridder     |                       |
                      +---------------+-----------------------+
                      |gravfft        |                       |
                      +---------------+-----------------------+
                      |grdflexure     |                       |
                      +---------------+-----------------------+
                      |grdgravmag3d   |                       |
                      +---------------+-----------------------+
                      |grdredpol      |                       |
                      +---------------+-----------------------+
                      |grdseamount    |                       |
                      +---------------+-----------------------+
                      |talwani2d      |                       |
                      +---------------+-----------------------+
                      |talwani3d      |                       |
                      +---------------+-----------------------+
                      |               | Supplement segy:      |
                      +---------------+-----------------------+
                      |pssegy         |                       |
                      +---------------+-----------------------+
                      |pssegyz        |                       |
                      +---------------+-----------------------+
                      |segy2grd       |                       |
                      +---------------+-----------------------+
                      |               | Supplement sph:       |
                      +---------------+-----------------------+
                      |sphdistance    |                       |
                      +---------------+-----------------------+
                      |sphinterpolate |                       |
                      +---------------+-----------------------+
                      |sphtriangulate |                       |
                      +---------------+-----------------------+
                      |               | Supplement spotter:   |
                      +---------------+-----------------------+
                      |backtracker    |                       |
                      +---------------+-----------------------+
                      |gmtpmodeler    |                       |
                      +---------------+-----------------------+
                      |grdpmodeler    |                       |
                      +---------------+-----------------------+
                      |grdrotater     |                       |
                      +---------------+-----------------------+
                      |grdspotter     |                       |
                      +---------------+-----------------------+
                      |hotspotter     |                       |
                      +---------------+-----------------------+
                      |originator     |                       |
                      +---------------+-----------------------+
                      |rotconverter   |                       |
                      +---------------+-----------------------+
                      |rotsmoother    |                       |
                      +---------------+-----------------------+


                      |               | Supplement x2sys:     |
                      +---------------+-----------------------+
                      |x2sys_binlist  |                       |
                      +---------------+-----------------------+
                      |x2sys_cross    |                       |
                      +---------------+-----------------------+
                      |x2sys_datalist |                       |
                      +---------------+-----------------------+
                      |x2sys_get      |                       |
                      +---------------+-----------------------+
                      |x2sys_init     |                       |
                      +---------------+-----------------------+
                      |x2sys_list     |                       |
                      +---------------+-----------------------+
                      |x2sys_merge    |                       |
                      +---------------+-----------------------+
                      |x2sys_put      |                       |
                      +---------------+-----------------------+
                      |x2sys_report   |                       |
                      +---------------+-----------------------+
                      |x2sys_solve    |                       |
                      +---------------+-----------------------+


CUSTOM MODULES

       The gmt program can also load  custom  modules  from  shared  libraries
       built as specified in the GMT API documentation.  This way your modules
       can benefit form the GMT infrastructure  and  extend  GMT  in  specific
       ways.


THE COMMON GMT OPTIONS

        -B[p|s]parameters -Jparameters -Jz|Zparameters -K -O -P
        -Rwest/east/south/north[/zmin/zmax][+r]
        -U[stamp]
        -V[level]
        -Xx_offset
        -Yy_offset  -aflags -bbinary -dnodata -fflags -ggaps -hheaders -iflags
       -nflags -oflags -pflags -r -sflags -ttransp -x[[-]n] -:[i|o]


DESCRIPTION

       These are all the common GMT options that remain the same for  all  GMT
       programs.  No  space  between  the option flag and the associated argu-
       ments.

       -B[p|s]parameters
              Set map Frame and Axes  parameters.  The  Frame  parameters  are
              specified by

              -B[axes][+b][+gfill][+n][+olon/lat][+ttitle]

              where  axes  selects  which  axes to plot. By default, all 4 map
              boundaries (or plot axes) are plotted (named W,  E,  S,  N).  To
              customize,  append  the  codes  for  those you want (e.g., WSn).
              Upper case means plot and annotate while lower case  just  plots
              the  specified  axes.   If a 3-D basemap is selected with -p and
              -Jz, append Z or z to control the  appearance  of  the  vertical
              axis.  By  default a single vertical axes will be plotted at the
              most suitable map corner. Override the default by appending  any
              combination  of  corner  ids  1234, where 1 represents the lower
              left corner and the order goes counter-clockwise. Append  +b  to
              draw the outline of the 3-D cube defined by -R; this modifier is
              also needed to display gridlines in the x-z,  y-z  planes.  Note
              that  for 3-D views the title, if given, will be suppressed. You
              can paint the interior of the canvas with +gfill.  Append +n  to
              have  no  frame and annotations at all [Default is controlled by
              the codes].  Optionally append +oplon/plat to draw oblique grid-
              lines about specified pole [regular gridlines]. Ignored if grid-
              lines are not requested (below) and disallowed for  the  oblique
              Mercator  projection.   To add a plot title (+ttitle). The Frame
              setting is optional but can be  invoked  once  to  override  the
              above defaults.

              The Axes parameters are specified by

              -B[p|s][x|y|z]intervals[+l|Llabel][+pprefix][+uunit]

              but  you  may  also split this into two separate invocations for
              clarity, i.e.,

       o -B[p|s][x|y|z][+l|Llabel][+pprefix][+uunit]

       o -B[p|s][x|y|z]intervals

         The first optional flag following -B selects p (rimary) [Default]  or
         s  (econdary)  axes  information  (mostly  used for time axes annota-
         tions).  The [x|y|z] flags  specify  which  axes  you  are  providing
         information  for.   If  none are given then we default to xy.  If you
         wish to give different annotation intervals or labels for the various
         axes  then  you  must  repeat  the  B  option for each axis (If a 3-D
         basemap is selected with -p and -Jz, use -Bz to give settings for the
         vertical  axis.).   To  add  a  label to an axis, just append +llabel
         (Cartesian projections only). Use +L to force a horizontal label  for
         y-axes (useful for very short labels).  If the axis annotation should
         have a leading text prefix (e.g., dollar sign for those plots of your
         net  worth) you can append +pprefix. For geographic maps the addition
         of degree symbols, etc. is  automatic  (and  controlled  by  the  GMT
         default setting FORMAT_GEO_MAP). However, for other plots you can add
         specific units by adding +uunit.  If any of these text  strings  con-
         tain  spaces or special UNIX characters you will need to enclose them
         in quotes.  The intervals specification is a concatenated string made
         up of substrings of the form

         [a|f|g]stride[+-phase][u].

         The  leading a is used to specify the annotation and major tick spac-
         ing [Default], f for minor tick spacing, and g for gridline  spacing.
         stride  is the desired stride interval. The optional phase shifts the
         annotation interval  by  that  amount  (positive  or  negative).  The
         optional unit indicates the unit of the stride and can be any of

         o Y (year, plot with 4 digits)

         o y (year, plot with 2 digits)

         o O (month, plot using FORMAT_DATE_MAP)

         o o (month, plot with 2 digits)

         o U (ISO week, plot using FORMAT_DATE_MAP)

         o u (ISO week, plot using 2 digits)

         o r (Gregorian week, 7-day stride from start of week TIME_WEEK_START)

         o K (ISO weekday, plot name of day)

         o D (date, plot using FORMAT_DATE_MAP)

         o d (day, plot day of month 0-31 or year 1-366, via FORMAT_DATE_MAP)

         o R (day, same as d, aligned with TIME_WEEK_START)

         o H (hour, plot using FORMAT_CLOCK_MAP)

         o h (hour, plot with 2 digits)

         o M (minute, plot using FORMAT_CLOCK_MAP)

         o m (minute, plot with 2 digits)

         o S (second, plot using FORMAT_CLOCK_MAP)

         o s (second, plot with 2 digits).

         Note for geographic axes m and s instead mean  arc  minutes  and  arc
         seconds.   All  entities that are language-specific are under control
         by GMT_LANGUAGE. Alternatively, for linear maps, we can omit  stride,
         thus  setting  xinfo, yinfo, or zinfo to a plots annotations at auto-
         matically determined intervals,

         o ag plots both annotations and grid lines with the same spacing,

         o afg adds suitable minor tick intervals,

         o g plots grid lines with the same interval as if -Bf was used.

         For custom annotations and intervals, let intervals be given as cint-
         file,  where  intfile  contains any number of records with coord type
         [label]. Here, type is one or more letters from a|i, f,  and  g.  For
         a|i  you  must supply a label that will be plotted at the coord loca-
         tion.  For non-geographical projections: Give negative scale (in -Jx)
         or axis length (in -JX) to change the direction of increasing coordi-
         nates (i.e., to make the y-axis  positive  down).   For  log10  axes:
         Annotations can be specified in one of three ways:

         1. stride  can  be  1, 2, 3, or -n. Annotations will then occur at 1,
            1-2-5, or 1-2-3-4-a|-9, respectively; for -n we annotate every nat
            magnitude.  This  option  can  also be used for the frame and grid
            intervals.

         2. An l is appended to the tickinfo string. Then, log10 of  the  tick
            value is plotted at every integer log10 value.

         3. A  p  is appended to the tickinfo string. Then, annotations appear
            as 10 raised to log10 of the tick value.

         For power axes: Annotations can be specified in one of two ways:

         1. stride sets the regular annotation interval.

         2. A p is appended to  the  tickinfo  string.  Then,  the  annotation
            interval  is  expected to be in transformed units, but the annota-
            tion value will be plotted as untransformed units. E.g., if stride
            =  1  and  power  = 0.5 (i.e., sqrt), then equidistant annotations
            labeled 1-4-9a|  will appear.

         These GMT parameters can affect the appearance of the  map  boundary:
         MAP_ANNOT_MIN_ANGLE,    MAP_ANNOT_MIN_SPACING,    FONT_ANNOT_PRIMARY,
         FONT_ANNOT_SECONDARY, MAP_ANNOT_OFFSET_PRIMARY, MAP_ANNOT_OFFSET_SEC-
         ONDARY,     MAP_ANNOT_ORTHO,     MAP_FRAME_AXES,     MAP_DEFAULT_PEN,
         MAP_FRAME_TYPE,   FORMAT_GEO_MAP,   MAP_FRAME_PEN,   MAP_FRAME_WIDTH,
         MAP_GRID_CROSS_SIZE_PRIMARY,                    MAP_GRID_PEN_PRIMARY,
         MAP_GRID_CROSS_SIZE_SECONDARY,  MAP_GRID_PEN_SECONDARY,   FONT_TITLE,
         FONT_LABEL,  MAP_LINE_STEP, MAP_ANNOT_OBLIQUE, FORMAT_CLOCK_MAP, FOR-
         MAT_DATE_MAP,   FORMAT_TIME_PRIMARY_MAP,   FORMAT_TIME_SECONDARY_MAP,
         GMT_LANGUAGE,     TIME_WEEK_START,    MAP_TICK_LENGTH_PRIMARY,    and
         MAP_TICK_PEN_PRIMARY; see the gmt.conf man page for details.

       -Jparameters

       Select map projection. The following character determines  the  projec-
       tion.  If  the character is upper case then the argument(s) supplied as
       scale(s) is interpreted to be the map width (or axis lengths), else the
       scale argument(s) is the map scale (see its definition for each projec-
       tion). UNIT is cm, inch, or point, depending  on  the  PROJ_LENGTH_UNIT
       setting  in gmt.conf, but this can be overridden on the command line by
       appending c, i, or p to the scale or width values. Append h, +, or - to
       the  given  width  if  you  instead want to set map height, the maximum
       dimension, or the minimum dimension, respectively  [Default  is  w  for
       width].   In  case the central meridian is an optional parameter and it
       is being omitted, then the center of the longitude range given  by  the
       -R  option  is used. The default standard parallel is the equator.  The
       ellipsoid used in the map projections is user-definable by editing  the
       gmt.conf  file  in your home directory. 73 commonly used ellipsoids and
       spheroids are currently supported, and users may also specify their own
       custom  ellipsoid  parameters [Default is WGS-84].  Several GMT parame-
       ters  can  affect  the  projection:  PROJ_ELLIPSOID,   GMT_INTERPOLANT,
       PROJ_SCALE_FACTOR,  and PROJ_LENGTH_UNIT; see the gmt.conf man page for
       details.  Choose one of the following projections (The  E  or  C  after
       projection names stands for Equal-Area and Conformal, respectively):
          CYLINDRICAL PROJECTIONS:
          -Jclon0/lat0/scale or -JClon0/lat0/width (Cassini).
              Give   projection   center   lon0/lat0   and  scale  (1:xxxx  or
              UNIT/degree).
          -Jcyl_stere/[lon0/[lat0/]]scale  or  -JCyl_stere/[lon0/[lat0/]]width
          (Cylindrical Stereographic).
              Give  central  meridian  lon0 (optional), standard parallel lat0
              (optional), and scale along parallel  (1:xxxx  or  UNIT/degree).
              The  standard parallel is typically one of these (but can be any
              value):

                 o 66.159467 - Milleras modified Gall

                 o 55 - Kamenetskiyas First

                 o 45 - Gallas Stereographic

                 o 30 - Bolshoi Sovietskii Atlas Mira or Kamenetskiyas Second

                 o 0 - Braunas Cylindrical
          -Jj[lon0/]scale or -JJ[lon0/]width (Miller Cylindrical  Projection).
              Give  the  central meridian lon0 (optional) and scale (1:xxxx or
              UNIT/degree).
          -Jm[lon0/[lat0/]]scale or -JM[lon0/[lat0/]]width (Mercator [C])
              Give central meridian lon0 (optional),  standard  parallel  lat0
              (optional), and scale along parallel (1:xxxx or UNIT/degree).
          -Joparameters (Oblique Mercator [C]).
              Typically used with -RLLx/LLy/URx/URyr or with projected coordi-
              nates.  Specify one of:

              -Jo[a|A]lon0/lat0/azimuth/scale                               or
              -JO[a|A]lon0/lat0/azimuth/width
                     Set projection center lon0/lat0, azimuth of oblique equa-
                     tor, and scale.

              -Jo[b|B]lon0/lat0/lon1/lat1/scale                             or
              -JO[b|B]lon0/lat0/lon1/lat1/scale
                     Set  projection  center  lon0/lat0,  another point on the
                     oblique equator lon1/lat1, and scale.

              -Joc|Clon0/lat0/lonp/latp/scale                               or
              -JOc|Clon0/lat0/lonp/latp/scale
                     Set projection center lon0/lat0, pole of oblique  projec-
                     tion  lonp/latp,  and  scale.   Give  scale along oblique
                     equator (1:xxxx or UNIT/degree).  The upper-case A|B|C to
                     removes enforcement of a northern hemisphere pole.
          -Jq[lon0/[lat0/]]scale    or   -JQ[lon0/[lat0/]]width   (Cylindrical
          Equidistant).
              Give the central meridian  lon0  (optional),  standard  parallel
              lat0 (optional), and scale (1:xxxx or UNIT/degree). The standard
              parallel is typically one of these (but can be any value):

                 o 61.7 - Grafarend and Niermann, minimum linear distortion

                 o 50.5 - Ronald Miller Equirectangular

                 o 43.5 - Ronald Miller, minimum continental distortion

                 o 42 - Grafarend and Niermann

                 o 37.5 - Ronald Miller, minimum overall distortion

                 o 0 - Plate Carree, Simple Cylindrical, Plain/Plane Chart
          -Jtlon0/[lat0/]scale or  -JTlon0/[lat0/]width  (Transverse  Mercator
          [C])
              Give   the   central   meridian   lon0,  central  parallel  lat0
              (optional), and scale (1:xxxx or UNIT/degree).
          -Juzone/scale or -JUzone/width (UTM - Universal Transverse  Mercator
          [C]).
              Give  the  UTM  zone  (A,B,1-60[C-X],Y,Z))  and scale (1:xxxx or
              UNIT/degree).  Zones: If C-X  not  given,  prepend  -  or  +  to
              enforce southern or northern hemisphere conventions [northern if
              south > 0].
          -Jy[lon0/[lat0/]]scale   or   -JY[lon0/[lat0/]]width    (Cylindrical
          Equal-Area [E]).
              Give  the  central  meridian  lon0 (optional), standard parallel
              lat0 (optional), and scale (1:xxxx or UNIT/degree). The standard
              parallel is typically one of these (but can be any value):

                 o 50 - Balthasart

                 o 45 - Gall-Peters

                 o 37.0666 - Caster

                 o 37.4 - Trystan Edwards

                 o 37.5 - Hobo-Dyer

                 o 30 - Behrman

                 o 0 - Lambert (default)

          CONIC PROJECTIONS:

          -Jblon0/lat0/lat1/lat2/scale or -JBlon0/lat0/lat1/lat2/width (Albers
          [E]).
                 Give  projection  center  lon0/lat0,  two  standard parallels
                 lat1/lat2, and scale (1:xxxx or UNIT/degree).

          -Jdlon0/lat0/lat1/lat2/scale or -JDlon0/lat0/lat1/lat2/width  (Conic
          Equidistant)
                 Give projection  center  lon0/lat0,  two  standard  parallels
                 lat1/lat2, and scale (1:xxxx or UNIT/degree).

          -Jllon0/lat0/lat1/lat2/scale  or  -JLlon0/lat0/lat1/lat2/width (Lam-
          bert [C])
                 Give  origin lon0/lat0, two standard parallels lat1/lat2, and
                 scale along these (1:xxxx or UNIT/degree).

          -Jpoly/[lon0/[lat0/]]scale or -JPoly/[lon0/[lat0/]]width ((American)
          Polyconic).
                 Give the central meridian lon0 (optional), reference parallel
                 lat0  (optional,  default = equator), and scale along central
                 meridian (1:xxxx or UNIT/degree).

          AZIMUTHAL PROJECTIONS:

          Except for polar aspects, -Rw/e/s/n  will  be  reset  to  -Rg.   Use
          -R<a|>r for smaller regions.

          -Jalon0/lat0[/horizon]/scale  or  -JAlon0/lat0[/horizon]/width (Lam-
          bert [E]).
                 lon0/lat0  specifies the projection center. horizon specifies
                 the max distance from projection center (in degrees, <=  180,
                 default 90). Give scale as 1:xxxx or radius/lat, where radius
                 is distance in UNIT from origin to the oblique latitude  lat.

          -Jelon0/lat0[/horizon]/scale     or     -JElon0/lat0[/horizon]/width
          (Azimuthal Equidistant).
                 lon0/lat0  specifies the projection center. horizon specifies
                 the max distance from projection center (in degrees, <=  180,
                 default  180).  Give  scale  as  1:xxxx  or radius/lat, where
                 radius is distance in UNIT from origin to the  oblique  lati-
                 tude lat.

          -Jflon0/lat0[/horizon]/scale     or     -JFlon0/lat0[/horizon]/width
          (Gnomonic).
                 lon0/lat0  specifies the projection center. horizon specifies
                 the max distance from projection center (in  degrees,  <  90,
                 default 60). Give scale as 1:xxxx or radius/lat, where radius
                 is distance in UNIT from origin to the oblique latitude  lat.

          -Jglon0/lat0[/horizon]/scale or -JGlon0/lat0[/horizon]/width (Ortho-
          graphic).
                 lon0/lat0  specifies the projection center. horizon specifies
                 the max distance from projection center (in degrees,  <=  90,
                 default 90). Give scale as 1:xxxx or radius/lat, where radius
                 is distance in UNIT from origin to the oblique latitude  lat.

          -Jglon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale       or
          -JGlon0/lat0/altitude/azimuth/tilt/twist/Width/Height/width (General
          Perspective).
                 lon0/lat0  specifies  the  projection center. altitude is the
                 height (in km) of the viewpoint above  local  sea  level.  If
                 altitude  is  less  than 10, then it is the distance from the
                 center of the earth to the viewpoint in earth radii. If alti-
                 tude  has a suffix r then it is the radius from the center of
                 the earth in kilometers. azimuth is measured to the  east  of
                 north  of  view. tilt is the upward tilt of the plane of pro-
                 jection. If tilt is negative, then the viewpoint is  centered
                 on  the horizon. Further, specify the clockwise twist, Width,
                 and Height of the viewpoint in degrees. Give scale as  1:xxxx
                 or  radius/lat,  where radius is distance in UNIT from origin
                 to the oblique latitude lat.

          -Jslon0/lat0[/horizon]/scale or  -JSlon0/lat0[/horizon]/width  (Gen-
          eral Stereographic [C]).
                 lon0/lat0 specifies the projection center. horizon  specifies
                 the  max  distance from projection center (in degrees, < 180,
                 default  90).  Give  scale  as  1:xxxx  (true  at  pole)   or
                 lat0/1:xxxx  (true  at  standard  parallel lat) or radius/lat
                 (radius in UNIT from origin to  the  oblique  latitude  lat).
                 Note  if 1:xxxx is used then to specify horizon you must also
                 specify the lat as +-90 to avoid ambiguity.

          MISCELLANEOUS PROJECTIONS:

          -Jh[lon0/]scale or -JH[lon0/]width (Hammer [E]).
                 Give the central meridian lon0  (optional)  and  scale  along
                 equator (1:xxxx or UNIT/degree).

          -Ji[lon0/]scale or -JI[lon0/]width (Sinusoidal [E]).
                 Give  the  central  meridian  lon0 (optional) and scale along
                 equator (1:xxxx or UNIT/degree).

          -Jkf[lon0/]scale or -JKf[lon0/]width (Eckert IV) [E]).
                 Give the central meridian lon0  (optional)  and  scale  along
                 equator (1:xxxx or UNIT/degree).

          -Jk[s][lon0/]scale or -JK[s][lon0/]width (Eckert VI) [E]).
                 Give  the  central  meridian  lon0 (optional) and scale along
                 equator (1:xxxx or UNIT/degree).

          -Jn[lon0/]scale or -JN[lon0/]width (Robinson).
                 Give the central meridian lon0  (optional)  and  scale  along
                 equator (1:xxxx or UNIT/degree).

          -Jr[lon0/]scale -JR[lon0/]width (Winkel Tripel).
                 Give  the  central  meridian  lon0 (optional) and scale along
                 equator (1:xxxx or UNIT/degree).

          -Jv[lon0/]scale or -JV[lon0/]width (Van der Grinten).
                 Give the central meridian lon0  (optional)  and  scale  along
                 equator (1:xxxx or UNIT/degree).

          -Jw[lon0/]scale or -JW[lon0/]width (Mollweide [E]).
                 Give  the  central  meridian  lon0 (optional) and scale along
                 equator (1:xxxx or UNIT/degree).

          NON-GEOGRAPHICAL PROJECTIONS:
          -Jp[a]scale[/origin][r|z] or -JP[a]width[/origin][r|z] (Polar  coor-
          dinates (theta,r))

          Optionally  insert  a after -Jp [ or -JP] for azimuths CW from North
          instead of directions CCW from  East  [Default].  Optionally  append
          /origin  in  degrees  to  indicate an angular offset [0]).  Finally,
          append r if r is elevations in degrees (requires s >= 0 and n <= 90)
          or  z  if  you  want to annotate depth rather than radius [Default].
          Give scale in UNIT/r-unit.
          -Jxx-scale[/y-scale] or -JXwidth[/height] (Linear,  log,  and  power
          scaling)

          Give  x-scale  (1:xxxx  or  UNIT/x-unit)  and/or  y-scale (1:xxxx or
          UNIT/y-unit);   or   specify   width   and/or   height   in    UNIT.
          y-scale=x-scale if not specified separately and using 1:xxxx implies
          that x-unit and y-unit are in  meters.   Use  negative  scale(s)  to
          reverse the direction of an axis (e.g., to have y be positive down).
          Set height or width to 0 to have it recomputed based on the  implied
          scale  of  the  other  axis. Optionally, append to x-scale, y-scale,
          width or height one of the following:

              d      Data are geographical coordinates (in degrees).

              l      Take log10 of values before scaling.

              ppower Raise values to power before scaling.

              t      Input coordinates are time relative to TIME_EPOCH.

              T      Input coordinates are absolute time.

              For mixed axes with only one geographic axis you may need to set
              -f  as well.  Default axis lengths (see gmt.conf) can be invoked
              using -JXh (for landscape); -JXv (for portrait) will swap the x-
              and  y-axis  lengths.  The default unit for this installation is
              either cm or inch, as defined in the file share/gmt.conf.   How-
              ever, you may change this by editing your gmt.conf file(s).

       When -J is used without any further arguments, or just with the projec-
       tion type, the arguments of the last used -J, or the last used -J  with
       that projection type, will be used.

       -Jz|Zparameters
              Set z-axis scaling; same syntax as -Jx.

       -K     More  PostScript code will be appended later [Default terminates
              the plot system]. Required for all but  the  last  plot  command
              when building multi-layer plots.

       -O     Selects  Overlay  plot mode [Default initializes a new plot sys-
              tem].  Required for all but the first plot command when building
              multi-layer plots.

       -P     Select  aPortraita plot orientation [Default is aLandscapea; see
              gmt.conf or gmtset to change the PS_PAGE_ORIENTATION  parameter,
              or   supply  --PS_PAGE_ORIENTATION=orientation  on  the  command
              line].

       -Rxmin/xmax/ymin/ymax[+r][+uunit]
              xmin, xmax, ymin, and ymax specify the region of interest.   For
              geographic  regions,  these  limits  correspond  to  west, east,
              south, and north 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
              west/east/south/north.  The two shorthands -Rg and -Rd stand for
              global domain (0/360 and -180/+180  in  longitude  respectively,
              with  -90/+90  in  latitude).   Alternatively for grid creation,
              give -Rcodex0/y0/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 x0/y0 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. When
              -R is used without any further arguments, the  values  from  the
              last use of -R in a previous GMT command will be used.  For cal-
              endar time coordinates you may either  give  (a)  relative  time
              (relative  to  the  selected  TIME_EPOCH  and  in  the  selected
              TIME_UNIT; append t to -JX|x), or (b) absolute time of the  form
              [date]T[clock]  (append  T  to  -JX|x). At least one of date and
              clock must be present; the T is always required. The date string
              must  be  of  the form [-]yyyy[-mm[-dd]] (Gregorian calendar) or
              yyyy[-Www[-d]] (ISO week calendar), while the clock string  must
              be  of  the form hh:mm:ss[.xxx]. The use of delimiters and their
              type and positions must be exactly as indicated (however, input,
              output  and  plot  formats are customizable; see gmt.conf).  You
              can also use Cartesian projected coordinates compatible with the
              chosen  projection.  Append the length unit via the +u modifier,
              (e.g., -R-200/200/-300/300+uk for a 400 by  600  km  rectangular
              area centered on the projection center (0, 0). These coordinates
              are internally converted to the corresponding geographic (longi-
              tude,  latitude)  coordinates for the lower left and upper right
              corners. This form is convenient when  you  want  to  specify  a
              region directly in the projected units (e.g., UTM meters).

       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.

       -U[[just]/dx/dy/][c|label]
              Draw Unix System time stamp on plot.  By  adding  [just]/dx/dy/,
              the  user  may  specify the justification of the stamp and where
              the stamp should fall on the page relative to lower left  corner
              of the plot.  For example, BL/0/0 will align the lower left cor-
              ner of the time stamp with the lower left  corner  of  the  plot
              [LL]. Optionally, append a label, or c (which will plot the com-
              mand string.). The GMT parameters  MAP_LOGO,  MAP_LOGO_POS,  and
              FORMAT_TIME_STAMP  can  affect  the appearance; see the gmt.conf
              man page for details. The time string will be in the locale  set
              by the environment variable TZ (generally local time).

       -V[level]
              Select verbose mode, which will send progress reports to stderr.
              Choose among 6 levels of verbosity; each level  adds  more  mes-
              sages:  q  - Complete silence, not even fatal error messages are
              produced.  n - Normal verbosity: produce only fatal  error  mes-
              sages.  c - Produce also compatibility warnings (same as when -V
              is omitted).  v - Produce also warnings  and  progress  messages
              (same as -V only).  l - Produce also detailed progress messages.
              d - Produce also debugging messages.

       -X[a|c|f|r][x-shift[u]]

       -Y[a|c|f|r][y-shift[u]]
              Shift  plot  origin  relative   to   the   current   origin   by
              (x-shift,y-shift)  and  optionally append the length unit (c, i,
              or p). You can prepend a to shift the origin back to the  origi-
              nal position after plotting, prepend c to center the plot on the
              center of the paper (optionally add shift), prepend f  to  shift
              the  origin relative to the fixed lower left corner of the page,
              or prepend r [Default] to move the origin relative to  its  cur-
              rent  location. If -O is used then the default (x-shift,y-shift)
              is (r0), otherwise it is (r1i). When -X or -Y are  used  without
              any  further  arguments,  the  values  from the last use of that
              option in a previous GMT command will be used.

       -a[col=]name[^<i>a|]
              Control how aspatial data are handled in GMT  during  input  and
              output.   Reading  OGR/GMT-formatted  files:  To  assign certain
              aspatial data items to  GMT  data  columns,  give  one  or  more
              comma-separated associations col=name, where name is the name of
              an aspatial attribute field in a OGR/GMT file and whose value we
              wish to use as data input for column col. In addition, to assign
              an aspatial value to non-column data, you may specify col  as  D
              for  distance,  G for fill, I for ID, L for label, T for text, W
              for pen, and Z for value [e.g., used to  look  up  color  via  a
              CPT].   If  you  skip the leading acol=a in the argument then we
              supply (and automatically increment) a column value starting  at
              2.   Writing OGR/GMT-formatted files: To write OGR/GMT-formatted
              files,   give   one   or   more   comma-separated   associations
              col=name[:type],  with an optional data type from DOUBLE, FLOAT,
              INTEGER, CHAR, STRING, DATETIME, or LOGICAL [DOUBLE]. To extract
              information  from GMT multisegment headers encoded in the -Ddis-
              tance, -Gfill, -IID, -Llabel, -Ttext,  -Wpen,  or  -Zvalue  set-
              tings,  specify COL as D, G, I, L, T, W or Z, respectively; type
              will be set automatically. Finally, you must append  +ggeometry,
              where  geometry  is  either  POINT,  LINE,  or POLY. Optionally,
              prepend M for multi-versions of these geometries. To  force  the
              clipping  of  features  crossing the Dateline, use upper-case +G
              instead. See GMT Appendix Q for details of the OGR/GMT file for-
              mat.

       -bi[ncols][type][w][+L|+B]
              Select  native  binary  input. Here, ncols is the number of data
              columns of given type, which must  be  one  of  c  (int8_t,  aka
              char), u (uint8_t, aka unsigned char), h (int16_t, 2-byte signed
              int), H (uint16_t, 2-byte  unsigned  int),  i  (int32_t,  4-byte
              signed  int),  I  ((capital i) uint32_t, 4-byte unsigned int), l
              ((lower case el)  int64_t,  8-byte  signed  int),  L  (uint64_t,
              8-byte  unsigned  int), f (4-byte single-precision float), and d
              (8-byte double-precision float). In  addition,  use  x  to  skip
              ncols  bytes  anywhere  in  the  record.  For records with mixed
              types, simply append additional comma-separated combinations  of
              ncolst.  Append  w  to any item to force byte-swapping. Alterna-
              tively, append +L|B to indicate that the entire data file should
              be  read  as little- or big-endian, respectively. The cumulative
              number of ncols may exceed the columns actually  needed  by  the
              program.  If  ncols is not specified we assume that type applies
              to all columns and that ncols is implied by the  expectation  of
              the  program. If the input file is netCDF, no -b is needed; sim-
              ply append ?var1/var2/^<i>a| to the filename to  specify  the  vari-
              ables to be read.

       -bo[ncols][type][w][+L|+B]
              Select native binary output. Here, ncols is the actual number of
              data columns of type t, which must be one of c, u, h,  H,  i,  I
              (capital  i), l (lower case elle), L, f, and d (see -bi).  For a
              mixed-type output record, append additional comma-separated com-
              binations  of ncols/t.  Append w to any item to force byte-swap-
              ping or +L|B for byte-swapping of the entire record. If ncols is
              not  specified  we assume that t applies to all columns and that
              ncols is implied by the default output  of  the  program.  Note:
              NetCDF file output is not supported.

       -d[i|o]nodata
              Control  how  user-coded  missing  data values are translated to
              official NaN values in GMT.  For input data we replace any value
              that  equals nodata with NaN. For output data we replace any NaN
              with the chosen nodata value.  Use -di or  -do  to  only  affect
              input or output.

       -dinodata
              Examine  all  input  columns  and  if  any item equals nodata we
              interpret this value as a missing data item and  substitute  the
              value NaN.

       -donodata
              Examine all output columns and if any item equals NAN we substi-
              tute it with the chosen missing data value nodata.

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i]
              Only accept ASCII data records that contains the specified  pat-
              tern.   To  reverse the search, i.e., to only accept data record
              that do not contain the specified pattern, use -e~. Should  your
              pattern happen to start with ~ you need to escape this character
              with a backslash [Default accepts all data records]. For  match-
              ing  data  records  against extended regular expressions enclose
              the expression in slashes.  Append i for case-insensitive match-
              ing.   For a list of such patterns, give +ffile with one pattern
              per line.  To give a single pattern starting with +f, escape  it
              with a backslash.

       -f[i|o]colinfo
              Specify  the  data types of input and/or output columns (time or
              geographical data). Specify i or o to make this  apply  only  to
              input or output [Default applies to both]. Give one or more col-
              umns (or column ranges) separated by commas, or use -f  multiple
              times  (column  ranges  must  be  given in the format start[:inc
              ]:stop, where inc defaults to 1 if  not  specified).   Append  T
              (absolute  calendar  time), t (relative time in chosen TIME_UNIT
              since TIME_EPOCH), x (longitude), y  (latitude),  p[unit]  (pro-
              jected x,y map coordinates in given unit [meter]) or f (floating
              point) to each column or column range item. Shorthands  -f[i|o]g
              means  -f[i|o]0x,1y  (geographic coordinates) and -f[i|o]c means
              -f[i|o]0-1f (Cartesian coordinates)

       -g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u]
              Examine the spacing between consecutive data points in order  to
              impose  breaks  in  the  line. Append x|X or y|Y to define a gap
              when there is a large enough change in the x or  y  coordinates,
              respectively, or d|D for distance gaps; use upper case to calcu-
              late gaps from projected coordinates. For gap-testing  on  other
              columns use [col]z; if col is not prepended the it defaults to 2
              (i.e., 3rd column).  Append [+|-]gap and optionally  a  unit  u.
              Regarding  optional signs: -ve means previous minus current col-
              umn value must exceed gap to be a gap, +ve means  current  minus
              previous  column  value  must  exceed gap, and no sign means the
              absolute value of the difference must exceed gap. For geographic
              data  (x|y|d),  the unit u may be arc degree, minute, or second,
              or meter [Default], foot, kilometer,  Mile,  nautical  mile,  or
              survey  foot. For projected data (X|Y|D), choose from inch, cen-
              timeter, or point [Default unit set by PROJ_LENGTH_UNIT].  Note:
              For  x|y|z  with  time  data  the  unit is instead controlled by
              TIME_UNIT. Repeat the option to specify  multiple  criteria,  of
              which  any  can  be  met to produce a line break. Issue an addi-
              tional -ga to indicate that all criteria must be met instead.

       -h[i|o][n][+c][+d][+rremark][+ttitle]
              Primary input file(s) has header record(s). If used, the default
              number  of  header  records  is IO_N_HEADER_RECS [1]. Use -hi if
              only the primary input data should have header records  [Default
              will  write  out  header  records  if the input data have them].
              Blank lines and lines starting with # are  always  skipped.  For
              output  you may request additional headers to be written via the
              option modifiers, and use +d to remove existing header  records.
              Append  +c  to  issue  a header comment with column names to the
              output [none].  Append +r to add a remark comment to the  output
              [none].   Append +t to add a title comment to the output [none].
              These optional strings may contain n to  indicate  line-breaks).
              If  used  with native binary data we interpret n to instead mean
              the number of bytes to skip on input or pad on output.

       -icols[+l][+sscale][+ooffset][,^<i>a|]
              Select specific data columns for  primary  input,  in  arbitrary
              order.  Columns not listed will be skipped. Give individual col-
              umns (or column ranges in the format  start[:inc  ]:stop,  where
              inc defaults to 1 if not specified) separated by commas [Default
              reads all columns in order, starting with the first column (0)].
              Columns  may be repeated.  To each column, optionally add any of
              the following:  +l  takes  log10  of  the  input  values  first;
              +sscale,  subsequently  multiplies by a given  scale factor [1];
              +ooffset, finally adds a given offset [0].

       -n[b|c|l|n][+a][+bBC][+c][+tthreshold]
              Select grid interpolation mode by adding b for B-spline  smooth-
              ing,  c for bicubic interpolation, l for bilinear interpolation,
              or n for nearest-neighbor value (for example to plot categorical
              data).  Optionally,  append +a to switch off antialiasing (where
              supported). Append +bBC  to  override  the  boundary  conditions
              used,  adding g for geographic, p for periodic, or n for natural
              boundary conditions. For the latter two you may append x or y to
              specify  just  one direction, otherwise both are assumed. Append
              +c to clip the interpolated grid to input z-min/max [Default may
              exceed limits]. Append +tthreshold to control how close to nodes
              with NaNs the interpolation will go. A threshold of 1.0 requires
              all (4 or 16) nodes involved in interpolation to be non-NaN. 0.5
              will interpolate about half way from a non-NaN value;  0.1  will
              go about 90% of the way, etc.  [Default is bicubic interpolation
              with antialiasing and a threshold of 0.5, using  geographic  (if
              grid is known to be geographic) or natural boundary conditions].

       -ocols[,a|]
              Select specific data columns for primary  output,  in  arbitrary
              order. Columns not listed will be skipped. Give columns (or col-
              umn ranges in the format start[:inc ]:stop, where  inc  defaults
              to  1  if  not  specified)  separated by commas.  Columns may be
              repeated.  [Default writes all columns in order].

       -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0]
              Selects perspective view and sets the azimuth and  elevation  of
              the  viewpoint  [180/90]. When -p is used in consort with -Jz or
              -JZ, a third value can be  appended  which  indicates  at  which
              z-level  all  2D  material,  like the plot frame, is plotted (in
              perspective). [Default is at the bottom of the z-axis]. Use  -px
              or  -py  to  plot  against  the  awalla  x  = level or y = level
              (default is on the horizontal plane, which is the same as  using
              -pz). For frames used for animation, you may want to append + to
              fix the center of your data  domain  (or  specify  a  particular
              world  coordinate  point with +wlon0/lat[/z]) which will project
              to the center of your page size (or specify the  coordinates  of
              the  projected  view point with +vx0/y0. When -p is used without
              any further arguments, the values from the last use of -p  in  a
              previous  GMT command will be used.  Alternatively, you can per-
              form a simple rotation about the z-axis by just giving the rota-
              tion  angle.   Optionally,  use  +v or +w to select another axis
              location than the plot origin.

       -r     Force pixel node registration  [Default  is  gridline  registra-
              tion].   (Node  registrations are defined in Section grid-regis-
              tration of the GMT Technical Reference and Cookbook.)

       -s[cols][a|r]
              Suppress output for records whose z-value  equals  NaN  [Default
              outputs  all  records].  Append a to skip records where at least
              one field equal NaN. Append r to reverse the suppression,  i.e.,
              only output the records whose z-value equals NaN. Alternatively,
              indicate a comma-separated list of all columns or column  ranges
              to  consider  for  this NaN test (Column ranges must be given in
              the format start[:inc ]:stop, where inc defaults  to  1  if  not
              specified).

       -t[transp]
              Set  PDF  transparency  level  for  an overlay, in 0-100 percent
              range. [Default is 0, i.e., opaque].

       -x[[-]n]
              Limit the number of cores  to  be  used  in  any  OpenMP-enabled
              multi-threaded  algorithms.  By default we try to use all avail-
              able cores.  Append n to only use n cores (if too large it  will
              be  truncated  to the maximum cores available).  Finally, give a
              negative n to select (all - n) cores (or at least 1 if n  equals
              or exceeds all).  The -x option is only available to GMT modules
              compiled with OpenMP support.

       -:[i|o]
              Swap 1st and 2nd column on input and/or output  [Default  is  no
              swapping].  Append  i to select input only or o to select output
              only. [Default affects both]. This option is typically  used  to
              handle     (latitude,     longitude)     files;     see     also
              -icols[l][sscale][ooffset][,^<i>a|].

       -^ 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.

   Specifying Color
       color  The color of lines, areas and patterns can  be  specified  by  a
              valid  color  name,  by  a gray shade (in the range 0-255), by a
              decimal color code (r/g/b, each in range  0-255;  h-s-v,  ranges
              0-360,  0-1,  0-1; or c/m/y/k, each in range 0-1), or by a hexa-
              decimal color code (#rrggbb, as used in HTML).  For  PDF  trans-
              parency,  append  @transparency in the 0-100 percent range [0 or
              opaque]. See gmtcolors for more information and a full  list  of
              color names.

   Specifying Fill
       fill   The attribute fill specifies the solid shade or solid color (see
              Specifying Color above) or the pattern used  for  filling  poly-
              gons.  Patterns are specified as ppattern, where pattern set the
              number of the built-in pattern (1-90) or the name  of  a  raster
              image  file. The optional +rdpi sets the resolution of the image
              [1200]. For 1-bit rasters: use upper case P  for inverse  video,
              or append +fcolor and/or +bcolor to specify fore- and background
              colors (use color = - for  transparency).  See  GMT  Cookbook  &
              Technical  Reference  Appendix  E  for information on individual
              built-in patterns.

   Specifying Fonts
       font   The attributes of text fonts as  defined  by  font  is  a  comma
              delimited  list  of  size,  fonttype  and fill, each of which is
              optional. size is the font size (usually in points) but c  or  i
              can be added to indicate other units. fonttype is the name (case
              sensitive!) of the font or its equivalent  numerical  ID  (e.g.,
              Helvetica-Bold  or  1).  fill specifies the gray shade, color or
              pattern of the text (see Specifying Fill above). Optionally, you
              may  append  =pen to the fill value in order to draw a text out-
              line. If you want to avoid that the outline  partially  obscures
              the  text,  append  append =~pen instead; in that case only half
              the linewidth is plotted on the outside of the font only.  If an
              outline  is  requested, you may optionally skip the text fill by
              setting it to -, in which case the  full  pen  width  is  always
              used.  If any of the font attributes is omitted their default or
              previous setting will be retained.

              The 35 available fonts are:

              0.   Helvetica

              1.   Helvetica-Bold

              2.   Helvetica-Oblique

              3.   Helvetica-BoldOblique

              4.   Times-Roman

              5.   Times-Bold

              6.   Times-Italic

              7.   Times-BoldItalic

              8.   Courier

              9.   Courier-Bold

              10.  Courier-Oblique

              11.  Courier-BoldOblique

              12.  Symbol

              13.  AvantGarde-Book

              14.  AvantGarde-BookOblique

              15.  AvantGarde-Demi

              16.  AvantGarde-DemiOblique

              17.  Bookman-Demi

              18.  Bookman-DemiItalic

              19.  Bookman-Light

              20.  Bookman-LightItalic

              21.  Helvetica-Narrow

              22.  Helvetica-Narrow-Bold

              23.  Helvetica-Narrow-Oblique

              24.  Helvetica-Narrow-BoldOblique

              25.  NewCenturySchlbk-Roman

              26.  NewCenturySchlbk-Italic

              27.  NewCenturySchlbk-Bold

              28.  NewCenturySchlbk-BoldItalic

              29.  Palatino-Roman

              30.  Palatino-Italic

              31.  Palatino-Bold

              32.  Palatino-BoldItalic

              33.  ZapfChancery-MediumItalic

              34.  ZapfDingbats

   Specifying Pens
       pen    The attributes of lines and symbol outlines as defined by pen is
              a  comma-delimited list of width, color and style, each of which
              is optional. width can be indicated  as  a  measure  (in  points
              (this  is  the  default),  centimeters,  or inches) or as faint,
              default, thin[ner|nest], thick[er|est], fat[ter|test], or obese.
              color  specifies  a  gray  shade  or color (see Specifying Color
              above). style can be any of asolida, adasheda or adotteda, or  a
              custom  combination  of  dashes  a-a and dots a.a. If any of the
              attributes is omitted their default or previous setting will  be
              retained.  See GMT Cookbook & Technical Reference Specifying pen
              attributes for more information.


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.


GRID FILE FORMATS

       By  default  GMT  writes  out  grid  as  single  precision  floats in a
       COARDS-complaint netCDF file format.  However, GMT is able  to  produce
       and  read  grid files in many other commonly used grid file formats and
       also facilitates so called apackinga of  grids,  writing  out  floating
       point  data  as  1- or 2-byte integers. To specify the precision, scale
       and offset, the user should add  the  suffix  =id[/scale/offset[/nan]],
       where id is a two-letter identifier of the grid type and precision, and
       scale and offset are optional scale factor and offset to be applied  to
       all grid values, and nan is the value used to indicate missing data. In
       case the two characters id is not provided, as in =/scale than a  id=nf
       is  assumed.  When reading grids, the format is generally automatically
       recognized from almost all of those formats that GMT and GDAL  combined
       offer.  If  not, the same suffix can be added to input grid file names.
       See grdconvert and Section grid-file-format of the GMT Technical Refer-
       ence and Cookbook for more information.

       When reading a netCDF file that contains multiple grids, GMT will read,
       by default, the first 2-dimensional grid that can find in that file. To
       coax  GMT  into  reading another multi-dimensional variable in the grid
       file, append ?varname to the file name, where varname is  the  name  of
       the variable. Note that you may need to escape the special meaning of ?
       in your shell program by putting a backslash in  front  of  it,  or  by
       placing  the  filename  and suffix between quotes or double quotes. The
       ?varname suffix can also be used for output grids to specify a variable
       name different from the default: aza. See grdconvert and Sections modi-
       fiers-for-CF and grid-file-format of the GMT  Technical  Reference  and
       Cookbook  for  more information, particularly on how to read splices of
       3-, 4-, or 5-dimensional grids.


SEE ALSO

       Look up the individual man pages for more details and full syntax.  Run
       gmt --help to list all GMT programs and to show all installation direc-
       tories. For an explanation of the various GMT settings in this man page
       (like FORMAT_FLOAT_OUT), see the man page of the GMT configuration file
       gmt.conf.  Information  is  also  available  on  the  GMT   home   page
       http://gmt.soest.hawaii.edu/


COPYRIGHT

       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe



5.4.2                            Jun 24, 2017                           gmt(1)

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