manpagez: man pages & more
man gmt(1)
Home | html | info | man
gmt(1)                                GMT                               gmt(1)




NAME

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


INTRODUCTION

       GMT is a collection of freely available command-line  tools  under  the
       GNU LGPL that allows you to manipulate x,y and x,y,z data sets (filter-
       ing, trend fitting, gridding, projecting, etc.) and  produce  illustra-
       tions  ranging from simple x-y plots, via contour maps, to artificially
       illuminated surfaces 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 completely 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
              Starts a given GMT module with the module-options  that  pertain
              to  that  particular  module.   A  few special commands are also
              available:

       gmt clear items
              Deletes current defaults, or the cache, data or sessions  direc-
              tories.   Choose  between defaults (deletes the current gmt.conf
              file used for the current modern session),  cache  (deletes  the
              useras  cache  directory  and all of its content), data (deletes
              the useras data download directory and all of its  content),  or
              all (does all of the above).

       gmt begin [session-prefix] [format] [options]
              Initializes  a  new  GMT  session  under modern mode [Default is
              classic mode].  All work is performed in a temporary work direc-
              tory.   The  optional  session-prefix assigns a name to the ses-
              sion, and this may be used as figure name for single-figure ses-
              sions  [gmtsession].   Likewise, the optional format can be used
              to override the default graphics format [PDF].

       gmt figure prefix [format(s)] [options]
              Specifies the desired name,  output  format(s)  and  any  custom
              arguments that should be passed to psconvert when producing this
              figure.  All subsequent plotting will be directed to  this  cur-
              rent  figure  until  another gmt figure command is issued or the
              session ends.  The prefix is used to build  final  figure  names
              when  extensions  are automatically appended. The format setting
              is a comma-separated list of desired extensions (e.g., pdf,png).

       gmt inset [arguments]
              Allows  users to place a map inset by temporarily changing where
              plotting takes place as well as the region and projection,  then
              resets to previous stage.

       gmt subplot [arguments]
              Allows  users to create a matrix of panels with automatic label-
              ing and advancement.

       gmt end [show]
              Terminates a GMT modern mode session and automatically  converts
              the  registered illustration(s) to their specified formats, then
              eliminates the temporary work directory.  The figures are placed
              in the current directory.

       For  information  on  any module, load the module documentation in your
       browser via gmt docs, e.g.:

          gmt docs grdimage

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

       --help List and description of GMT modules.

       --new-script[=L]
              Write a GMT modern mode script template  to  stdout.  Optionally
              append the desired scripting language among bash, csh, or batch.
              Default is the main shell closest to your current  shell  (e.g.,
              bash for zsh, csh for tcsh).

       --new-glue=name
              Write  the  C code glue needed when building third-party supple-
              ments as shared libraries.  The name is the name of  the  shared
              library. Run gmt in the directory of the supplement and the glue
              code will be written to stdout.   Including  this  C  code  when
              building the shared library means gmt can list available modules
              via the --show-modules, --help options.  We recommend saving the
              code to gmt_name_glue.c.

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

       --show-citation
              Show the citation for the latest GMT publication.

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

       --show-classic-core
              List classic module names (core only) on stdout and exit.

       --show-cores
              Show number of available cores.

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

       --show-dataserver
              Show URL of the remote GMT data server.

       --show-doi
              Show the DOI of the current release.

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

       --show-modules-core
              List modern module names (core only) on stdout and exit.

       --show-library
              Show the path of the shared GMT library.

       --show-plugindir
              Show plugin directory and exit.

       --show-sharedir
              Show share directory and exit.

       --show-userdir
              Show full path of useras ~/.gmt dir 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 MODULES

       Run  gmt --help to print the list of all core and supplementals modules
       within GMT, and a very short description of  their  purpose.   Detailed
       information  about  each  program  can  be found in the separate manual
       pages.


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 from the GMT infrastructure  and  extend  GMT  in  specific
       ways.


THE COMMON GMT OPTIONS

       -B[p|s]parameters              -Jparameters             -Jz|Zparameters
       -Rwest/east/south/north[/zmin/zmax][+r][+uunit]   -U[stamp]   -V[level]
       -X[a|c|f|r][xshift]    -Y[a|c|f|r][yshift]    -aflags    -bbinary   -c-
       row,col|index -dnodata -eregexp -fflags -ggaps  -hheaders  -iflags  -j-
       flags  -lflags  -nflags  -oflags -pflags -qflags -rreg -sflags -ttransp
       -x[[-]n] -:[i|o]


DESCRIPTION

       These are all the common GMT options that remain the same for  all  GMT
       modules. No space between the option flag and the associated arguments.

   The -B option
       Syntax

       -B[p|s]parameters
              Set map boundary frame and axes attributes. (See cookbook infor-
              mation).

       Description

       This  is potentially the most complicated option in GMT, but most exam-
       ples of its usage are actually quite simple. We distinguish between two
       sets  of  information: Frame settings and Axes settings.  These are set
       separately by their own -B invocations; hence  multiple  -B  specifica-
       tions  may  be specified. The Frame settings cover things such as which
       axes should be plotted, canvas fill, plot  title  (and  subtitle),  and
       what  type  of  gridlines be drawn, whereas the Axes settings deal with
       annotation, tick, and gridline intervals, axes labels,  and  annotation
       units.

   Frame settings
       The Frame settings are specified by
          -B[axes][+b][+gfill][+i[val]][+n][+olon/lat][+ssubtitle][+tti-
          tle][+w[pen]][+xfill][+yfill][+zfill]

       The frame setting is optional but can be invoked once to  override  the
       defaults.  The following modifiers can be appended to -B to control the
       Frame settings:

       o axes to set which of the axes should be drawn and possibly  annotated
         using  a  combination  of  the  codes  listed below [default is theme
         dependent]. Borders omitted from the set of codes will not be  drawn.
         For  example,  WSn  denotes  that the awesterna (left) and asoutherna
         (bottom) axes should be drawn  with  tick-marks  and  annotations  by
         using  W  and S; that the anortherna (top) edge of the plot should be
         drawn with tick-marks and without annotations by using  n;  and  that
         the  aeasterna  (right) axes should not be drawn by not including one
         of E|e|r.

            o West, East, South, North, and/or (for 3-D plots) Z indicate axes
              that should be drawn with both tick-marks and annotations.

            o west, east, south, north, and/or (for 3-D plots) z indicate axes
              that should be drawn with tick-marks but without annotations.

            o l(eft), r(ight), b(ottom), t(op) and/or  (for  3-D  plots)  u(p)
              indicate axes that should be drawn without tick-marks or annota-
              tions.

       o Z|zcode (for 3-D plots) where code is any combination of  the  corner
         ids  1,  2, 3, 4.  By default, a single vertical axes will be plotted
         for 3-D plots at the most suitable map corner. code can  be  used  to
         override this, where 1 represents the south-western (lower-left) cor-
         ner,  2  the  south-eastern  (lower-right),   3   the   north-eastern
         (upper-right), and 4 the north-western (upper-left) corner.

       o +w[pen]  (for  3-D  plots)  to  draw  the outlines of the x-z and y-z
         planes [default is no outlines]. Optionally, append  pen  to  specify
         different pen attributes [default is MAP_GRID_PEN_PRIMARY].

       o +b  (for  3-D  plots)  to  draw  the foreground lines of the 3-D cube
         defined by -R.

       o +gfill to paint the interior of the canvas with a color specified  by
         fill [default is no fill]. This also sets fill for the two back-walls
         in 3-D plots.

       o +xfill to paint the yz plane with a color specified by fill  [default
         is no fill].

       o +yfill  to paint the xz plane with a color specified by fill [default
         is no fill].

       o +zfill to paint the xy plane with a color specified by fill  [default
         is no fill].

       o +i[val]  to  annotate  an internal meridian or parallel when the axis
         that normally would be drawn and annotated does not exist (e.g.,  for
         an azimuthal map with 360-degree range that has no latitude axis or a
         global Hammer map that has no longitude axis). val gives the meridian
         or parallel that should be annotated [default is 0].

       o +olon/lat  to  produce oblique gridlines about another pole specified
         by lon/lat [default references to the North pole]. +o is  ignored  if
         no gridlines are requested.

       o +n  to  have no frame and annotations at all [default is contolled by
         axes].

       o +ttitle to place the string given in title centered  above  the  plot
         frame [default is no title].

       o +ssubtitle  (requires  +ttitle) to place the string given in subtitle
         beneath the title [default is no subtitle].

       Note: Both +ttitle and +ssubtitle may be set  over  multiple  lines  by
       breaking  them  up  using  the markers @^ or <break>.  To include LaTeX
       code as part of a single-line title or subtitle, enclose the expression
       with  @[  markers  (or alternatively <math> a| </math>) (requires latex
       and dvips to be installed). See  the  /cookbook/gmt-latex  chapter  for
       more details.

   Axes settings
       The Axes settings are specified by
          -B[p|s][x|y|z]intervals[+aangle|n|p][+f][+llabel][+pprefix][+uunit]

       but  you may also split this into two separate invocations for clarity,
       i.e.,
          -B[p|s][x|y|z][+aangle|n|p][+f][+l|Llabel][+pprefix][+s|Sseclabel][+uunit]
          -B[p|s][x|y|z]intervals


       The following modifiers can be appended to -B to control the Axes  set-
       tings:

       o p|s   to  set  whether  the  modifiers  apply  to  the  p(rimary)  or
         s(econdary) axes [Default is p].  These settings are mostly used  for
         time  axes annotations but are available for geographic axes as well.
         Note: Primary refers to annotations closest to the axis and secondary
         to  annotations further away.  Hence, primary annotation-, tick-, and
         gridline-intervals must be shorter than their secondary counterparts.
         The  terms  aprimarya and asecondarya do not reflect any hierarchical
         order of units: the aprimarya annotation interval is usually  smaller
         (e.g.,  days)  while the asecondarya annotation interval typically is
         larger (e.g., months).

       o x|y|z to set which axes the modifiers apply to [default  is  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.  For  a
         3-D plot with the -p and -Jz options used, -Bz can be used to provide
         settings for the verical axis.

       o +f (for geographic axes only) to give fancy annotations with  W|E|S|N
         suffices encoding the sign.

       o +l|+Llabel  (for  Cartesian plots only) to add a label to an axis. +l
         uses the default label orientation; +L forces a horizontal label  for
         y-axes, which is useful for very short labels.

       o +s|Sseclabel (for Cartesion plots only) to specify an alternate label
         for the right or upper axes.  +s uses the default label  orientation;
         +S  forces  a  horizontal  label for y-axes, which is useful for very
         short labels.

       o +pprefix (for Cartesion plots only) to define a leading  text  prefix
         for  the  axis  annotation  (e.g.,  dollar  sign for plots related to
         money). For geographic maps the addition of degree symbols,  etc.  is
         automatic and controlled by FORMAT_GEO_MAP.

       o +uunit  (for  Cartesion  plots  only) to append specific units to the
         annotations. For geographic maps the addition of degree symbols, etc.
         is automatic and controlled by FORMAT_GEO_MAP.

       o +aangle (for Cartesion plots only) to plot slanted annotations, where
         angle is measured with respect to the horizontal and must be  in  the
         -90  <=  angle <= 90 range. +an can be used as a shorthand for normal
         (i.e., +a90) [Default for y-axis] and +ap for  parallel  (i.e.,  +a0)
         annotations  [Default  for x-axis]. These defaults can be changed via
         MAP_ANNOT_ORTHO.

       o intervals to define the intervals  for  annotations  and  major  tick
         spacing,  minor tick spacing, and/or grid line spacing. See Intervals
         Specification for the formatting associated with this modifier.

       NOTE: To include LaTeX code as part of a label, enclose the  expression
       with  @[  markers (or alternatively <math> a| </math>). (requires latex
       and dvips to be installed). See  the  /cookbook/gmt-latex  chapter  for
       more details.

       NOTE: If any labels, prefixes, or units contain spaces or special char-
       acters you will need to enclose them in quotes.

       NOTE: Text items such as title, subtitle, label and seclabel  are  seen
       by  GMT  as  part  of a long string containing everything passed to -B.
       Therefore, they cannot contain substrings that look  like  other  modi-
       fiers.  If  you  need to embed such sequences (e.g., +taSolving a+b=ca)
       you need to replace those + symbols with their octal  equivalent  \053,
       (e.g., +taSolving a\053b=ca).

       NOTE: For non-geographical projections: Give negative scale (in -Jx) or
       axis length (in -JX) to change the direction of increasing  coordinates
       (i.e., to make the y-axis positive down).
       Intervals specification
       The intervals specification is a concatenated string made up of substrings of the form

          [a|f|g][stride][phase][unit].

       The  choice of a|f|g sets the axis item of interest, which are detailed
       in the Table interval types. Optionally,  append  phase  to  shift  the
       annotations  by  that  amount (positive or negative with the sign being
       required). Optionally, append unit to  specify  the  units  of  stride,
       where  unit  is  one of the 18 supported unit codes. For custom annota-
       tions and intervals, intervals can be given as cintfile, where  intfile
       contains any number of records with coord type [label]. See the section
       Custom axes for more details.

                         +-----+----------------------------+
                         |Flag | Description                |
                         +-----+----------------------------+
                         |a    | Annotation and major  tick |
                         |     | spacing                    |
                         +-----+----------------------------+
                         |f    | Minor tick spacing         |
                         +-----+----------------------------+
                         |g    | Grid line spacing          |
                         +-----+----------------------------+

       NOTE:  The  appearance  of certain time annotations (month-, week-, and
       day-names)  may  be  affected  by  the  GMT_LANGUAGE,  FORMAT_TIME_PRI-
       MARY_MAP, and FORMAT_TIME_SECONDARY_MAP settings.

       Automatic intervals: GMT will auto-select the spacing between the anno-
       tations and major ticks, minor ticks, and grid lines if stride  is  not
       provided  after a|f|g. This can be useful for automated plots where the
       region may not always be the same, making it difficult to determine the
       appropriate stride in advance. For example, -Bafg will select all three
       spacings automatically for both axes.  In  case  of  longitudealatitude
       plots,  this  will keep the spacing the same on both axes. You can also
       use -Bxafg -Byafg to auto-select them separately. Note that  given  the
       myriad  ways  of specifying time-axis annotations, the automatic selec-
       tions may need to be overridden with manual settings to achieve exactly
       what you need. When stride is omitted after g, the grid line are spaced
       the same as the minor ticks; unless g is used in  consort  with  a,  in
       which case the grid lines are spaced the same as the annotations.

       Stride  units:  The  unit  flag  can  take on one of 18 codes which are
       listed in Table Units. Almost all of these  units  are  time-axis  spe-
       cific.  However,  the  d,  m,  and  s  units will be interpreted as arc
       degrees, minutes, and arc seconds respectively when a map projection is
       in effect.

                    +-----+----------------+---------------------+
                    |Flag | Unit           | Description         |
                    +-----+----------------+---------------------+

                    |Y    | year           | Plot  using  all  4 |
                    |     |                | digits              |
                    +-----+----------------+---------------------+
                    |y    | year           | Plot using  last  2 |
                    |     |                | digits              |
                    +-----+----------------+---------------------+
                    |O    | month          | Format   annotation |
                    |     |                | using          FOR- |
                    |     |                | MAT_DATE_MAP        |
                    +-----+----------------+---------------------+
                    |o    | month          | Plot   as   2-digit |
                    |     |                | integer (1a12)      |
                    +-----+----------------+---------------------+
                    |U    | ISO week       | Format   annotation |
                    |     |                | using          FOR- |
                    |     |                | MAT_DATE_MAP        |
                    +-----+----------------+---------------------+
                    |u    | ISO week       | Plot   as   2-digit |
                    |     |                | integer (1a53)      |
                    +-----+----------------+---------------------+
                    |r    | Gregorian week | 7-day  stride  from |
                    |     |                | start of week  (see |
                    |     |                | TIME_WEEK_START)    |
                    +-----+----------------+---------------------+
                    |K    | ISO weekday    | Plot  name of week- |
                    |     |                | day   in   selected |
                    |     |                | language            |
                    +-----+----------------+---------------------+
                    |k    | weekday        | Plot  number of day |
                    |     |                | in the  week  (1a7) |
                    |     |                | (see                |
                    |     |                | TIME_WEEK_START)    |
                    +-----+----------------+---------------------+
                    |D    | date           | Format   annotation |
                    |     |                | using          FOR- |
                    |     |                | MAT_DATE_MAP        |
                    +-----+----------------+---------------------+
                    |d    | day            | Plot day  of  month |
                    |     |                | (1a31)  or  day  of |
                    |     |                | year  (1a366)  (see |
                    |     |                | FORMAT_DATE_MAP)    |
                    +-----+----------------+---------------------+
                    |R    | day            | Same  as d; annota- |
                    |     |                | tions aligned  with |
                    |     |                | week           (see |
                    |     |                | TIME_WEEK_START)    |
                    +-----+----------------+---------------------+
                    |H    | hour           | Format   annotation |
                    |     |                | using          FOR- |
                    |     |                | MAT_CLOCK_MAP       |
                    +-----+----------------+---------------------+
                    |h    | hour           | Plot   as   2-digit |
                    |     |                | integer (0a24)      |
                    +-----+----------------+---------------------+
                    |M    | minute         | Format   annotation |
                    |     |                | using          FOR- |
                    |     |                | MAT_CLOCK_MAP       |
                    +-----+----------------+---------------------+
                    |m    | minute         | Plot   as   2-digit |
                    |     |                | integer (0a60)      |
                    +-----+----------------+---------------------+
                    |S    | seconds        | Format   annotation |
                    |     |                | using          FOR- |
                    |     |                | MAT_CLOCK_MAP       |
                    +-----+----------------+---------------------+



                    |s    | seconds        | Plot   as   2-digit |
                    |     |                | integer (0a60)      |
                    +-----+----------------+---------------------+

       NOTE:  If your axis is in radians you can use multiples or fractions of
       pi to set such annotation intervals. The format  is  [s]pi[f],  for  an
       optional  integer  scale  s  and  optional integer fraction f. When GMT
       parses one of these forms we alert the labeling machinery to  look  for
       certain  combinations  of  pi, limited to npi, 3/2 pi (3pi2), and frac-
       tions 3/4 (3pi4), 2/3 (2pi3), 1/2 (1pi2), 1/3 (1pi3), and 1/4 (1pi4) in
       the interval given to the -B axes settings.  When an annotated value is
       within roundoff-error of these combinations we typeset the label  using
       the Greek letter \pi and required multiples or fractions.

       NOTE:  These GMT parameters can affect the appearance of the map bound-
       ary:
              MAP_ANNOT_MIN_ANGLE,  MAP_ANNOT_MIN_SPACING, FONT_ANNOT_PRIMARY,
              FONT_ANNOT_SECONDARY,  MAP_ANNOT_OFFSET_PRIMARY,  MAP_ANNOT_OFF-
              SET_SECONDARY, 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, FOR-
              MAT_CLOCK_MAP,  FORMAT_DATE_MAP,  FORMAT_TIME_PRIMARY_MAP,  FOR-
              MAT_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.

   The -J option
       Syntax

       -Jparameters
              Specify  the projection. (See cookbook summary) (See projections
              table).

       Description

       Select map projection. The first character of parameters determines the
       projection.  If  the  character is upper case then the argument(s) sup-
       plied 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 projection). The measurement unit (called UNIT below) 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 +dh, +du, or +dl to the given width
       if you instead want to set the map height, the maximum  (upper)  dimen-
       sion,  or  the  minimum (lower) dimension, respectively [Default is +dw
       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 map projections is user-definable. 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  parameters  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
       and  append  the required parameters (The E or C after projection names
       stands for Equal-Area and Conformal, respectively):
          CYLINDRICAL PROJECTIONS:
          -Jc|Clon0/lat0/scale|width (Cassini).
              Give projection center lon0/lat0 and either scale (with -Jc;  as
              1:xxxx or plot-units/degree) or width (with -JC; in plot-units).
          -Jcyl_stere|Cyl_stere/[lon0/[lat0/]]scale|width (Cylindrical Stereo-
          graphic)
              Give  central  meridian  lon0 (optional), standard parallel lat0
              (optional), and either scale along parallel  (with  -Jcyl_stere;
              as  1:xxxx  or plot-units/degree) or width (with -JCyc_stere; in
              plot-units). 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|J[lon0/]scale|width (Miller Cylindrical Projection).
              Give the central meridian lon0 (optional) and either scale (with
              -Jj; as 1:xxxx or plot-units/degree)  or  width  (with  -JJ;  in
              plot-units).
          -Jm|M[lon0/[lat0/]]scale|width (Mercator [C])
              Give  central  meridian  lon0 (optional), standard parallel lat0
              (optional), and either scale along parallel (with -Jm; as 1:xxxx
              or plot-units/degree) or width (with -JM; in plot-units).
          -Joparameters[+v] (Oblique Mercator [C]).
              Typically  used with -RLLx/LLy/URx/URy+r or with projected coor-
              dinates.  Specify one of:

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

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

              -Jo|O[c|C]lon0/lat0/lonp/latp/scale|width[+v]
                     Set projection center lon0/lat0, pole of oblique  projec-
                     tion lonp/latp, and scale or width

              Give  scale  along  oblique  equator  (with  -Ja|b|c;  1:xxxx or
              plot-units/degree) or width (with -JA|B|C; in  plot-units).  Use
              upper-case  A|B|C to remove enforcement of a northern hemisphere
              pole. Append +v to let the oblique Equator align with the y-axis
              [x-axis].  Note: If the region (-R) is given without the +r mod-
              ifier then the arguments are considered oblique degrees relative
              to the projection center and not longitude/latitude bounds.
          -Jq|Q[lon0/[lat0/]]scale|width (Cylindrical Equidistant).
              Give  the  central  meridian  lon0 (optional), standard parallel
              lat0 (optional), and  either  scale  (with  -Jq;  as  1:xxxx  or
              plot-units/degree)  or width (with -JQ; in plot-units) The stan-
              dard 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
          -Jt|Tlon0/[lat0/]scale|width (Transverse Mercator [C])
              Give  the  central  meridian   lon0,   central   parallel   lat0
              (optional),   and   either   scale   (with  -Jt;  as  1:xxxx  or
              plot-units/degree) or width (with -JT; in plot-units).
          -Ju|Uzone/scale|width (UTM - Universal Transverse Mercator [C]).
              Give the UTM zone (A,B,1-60[C-X],Y,Z)) and  either  scale  (with
              -Ju;  as  1:xxxx  or  plot-units/degree)  or width (with -JU; in
              plot-units). Zones: If C-X not given, prepend - or + to  enforce
              southern or northern hemisphere conventions [default is northern
              if south > 0].
          -Jy|Y[lon0/[lat0/]]scale|width (Cylindrical Equal-Area [E]).
              Give the central meridian  lon0  (optional),  standard  parallel
              lat0  (optional),  and  either  scale  (with  -Jy;  as 1:xxxx or
              plot-units/degree) or width (with -JY; in plot-units). The stan-
              dard parallel is typically one of these (but can be any value):

                 o 50 - Balthasart

                 o 45 - Gall

                 o 37.0666 - Caster

                 o 37.4 - Trystan Edwards

                 o 37.5 - Hobo-Dyer

                 o 30 - Behrman

                 o 0 - Lambert (default)

          CONIC PROJECTIONS:

          -Jb|Blon0/lat0/lat1/lat2/scale|width (Albers [E]).
                 Give  projection  center  lon0/lat0,  two  standard parallels
                 lat1/lat2,  and  either  scale  (with  -Jb;  as   1:xxxx   or
                 plot-units/degree) or width (with -JB; in plot-units).

          -Jd|Dlon0/lat0/lat1/lat2/scale|width (Conic Equidistant)
                 Give  projection  center  lon0/lat0,  two  standard parallels
                 lat1/lat2,  and  either  scale  (with  -Jd;  as   1:xxxx   or
                 plot-units/degree) or width (with -JD; in plot-units).

          -Jl|Llon0/lat0/lat1/lat2/scale|width (Lambert [C])
                 Give  origin lon0/lat0, two standard parallels lat1/lat2, and
                 scale along these (with -Jl; as 1:xxxx or  plot-units/degree)
                 or width (with -JL; in plot-units).

          -Jpoly|Poly/[lon0/[lat0/]]scale|width ((American) Polyconic).
                 Give the central meridian lon0 (optional), reference parallel
                 lat0 (optional, default = equator), and  either  scale  along
                 central    meridian    (with    -Jpoly;    as    1:xxxx    or
                 plot-units/degree) or width (with -JPoly; in plot-units).

          AZIMUTHAL PROJECTIONS:

          Except for polar aspects,  -Rw/e/s/n  will  be  reset  to  -Rg.  Use
          -Rxlleft/ylleft/xuright/yuright+r for smaller regions.

          -Ja|Alon0/lat0[/horizon]scale|width (Lambert [E]).
                 lon0/lat0  specifies the projection center. horizon specifies
                 the max distance from projection center (in degrees, <=  180,
                 default  90).  Give  either  scale  (with  -Ja;  as 1:xxxx or
                 radius/lat, where radius is distance in plot-units from  ori-
                 gin  to  the  oblique  latitude  lat)  or width (with -JA; in
                 plot-units).

          -Je|Elon0/lat0[/horizon]scale|width (Azimuthal Equidistant).
                 lon0/lat0 specifies the projection center. horizon  specifies
                 the  max distance from projection center (in degrees, <= 180,
                 default 180). Give scale (with -Je; as 1:xxxx or  radius/lat,
                 where  radius  is  distance  in plot-units from origin to the
                 oblique latitude lat) or width (with -JE; in plot-units).

          -Jf|Flon0/lat0[/horizon]scale|width (Gnomonic).
                 lon0/lat0 specifies the projection center. horizon  specifies
                 the  max  distance  from projection center (in degrees, < 90,
                 default 60). Give scale (with -Jf; as 1:xxxx  or  radius/lat,
                 where  radius  is  distance  in plot-units from origin to the
                 oblique latitude lat) or width (with -JF; in plot-units).

          -Jg|Glon0/lat0[/horizon]/scale|width (Orthographic).
                 lon0/lat0 specifies the projection center. horizon  specifies
                 the  max  distance from projection center (in degrees, <= 90,
                 default 90). Give scale (with -Jg; as 1:xxxx  or  radius/lat,
                 where  radius  is  distance  in plot-units from origin to the
                 oblique latitude lat.

          -Jg|Glon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale|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 (with -Jg;
                 as  1:xxxx  or  radius/lat,  where  radius  is  distance   in
                 plot-units  from origin to the oblique latitude lat) or width
                 (with -JG; in plot-units).

          -Js|Slon0/lat0[/horizon]/scale|width (General Stereographic [C]).
                 lon0/lat0 specifies the projection center. horizon  specifies
                 the  max  distance from projection center (in degrees, < 180,
                 default 90). Give scale (with -Js; as 1:xxxx (true  at  pole)
                 or  lat0/1:xxxx (true at standard parallel lat) or radius/lat
                 (radius in plot-units 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.)  or  width
                 (with -JS; in plot-units).

          MISCELLANEOUS PROJECTIONS:

          -Jh|H[lon0/]scale|width (Hammer [E]).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jh; as 1:xxxx or  plot-units/degree)  or
                 width (with -JH; in plot-units).

          -Ji|I[lon0/]scale|width (Sinusoidal [E]).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Ji; as 1:xxxx or  plot-units/degree)  or
                 width (with -JI; in plot-units).

          -Jk|Kf[lon0/]scale|width (Eckert IV [E]).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jk; as 1:xxxx or  plot-units/degree)  or
                 width (with -JK; in plot-units).

          -Jk|K[s][lon0/]scale|width (Eckert VI [E]).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jk; as 1:xxxx or  plot-units/degree)  or
                 width (with -JK; in plot-units).

          -Jn|N[lon0/]scale|width (Robinson).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jn; as 1:xxxx or  plot-units/degree)  or
                 width (with -JN; in plot-units).

          -Jr|R[lon0/]scale|width (Winkel Tripel).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jr; as 1:xxxx or  plot-units/degree)  or
                 width (with -JR; in plot-units).

          -Jv|V[lon0/]scale|width (Van der Grinten).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jv; as 1:xxxx or  plot-units/degree)  or
                 width (with -JV; in plot-units).

          -Jw|W[lon0/]scale|width (Mollweide [E]).
                 Give  the  central  meridian lon0 (optional) and either scale
                 along equator (with -Jw; as 1:xxxx or  plot-units/degree)  or
                 width (with -JW; in plot-units).

          NON-GEOGRAPHICAL PROJECTIONS:
          -Jp|Pscale|width[+a][+f[e|p|radius]][+kkind][+roffset][+tori-
          gin][+z[p|radius]]] (Polar coordinates (theta, r))

          Give scale (with -Jp; in plot-units/r-unit) or width (with  -JP;  in
          plot-units). The following modifiers are supported by -Jp|P:

          o +a  to  indicate  that  theta  is azimuth CW from North instead of
            direction CCW from East [Default is CCW from East].

          o +f to flip the radial direction to point inwards, and append e  to
            indicate  that  r represents elevations in degrees (requires south
            >= 0 and north <=  90),  p  to  select  current  planetary  radius
            (determined  by  PROJ_ELLIPSOID)  as  maximum  radius  [north], or
            radius to specify a custom radius.

          o +k sets the annotation kind to be longitudes (x) or latitudes  (y)
            [Default is unspecified angles].

          o +roffset  to include a radial offset in measurement units [default
            is 0].

          o +torigin in degrees so that this angular value is aligned with the
            positive  x-axis  (or  the azimuth to be aligned with the positive
            y-axis if +a) [default is 0].

          o +z to annotate depth  rather  than  radius  [default  is  radius].
            Alternatively,  if  your  r  data are actually depths then you can
            append p or radius to get radial annotations  (r  =  radius  -  z)
            instead.
          -Jx|Xx-scale|width[l|ppower|T|t][/y-scale|height[l|ppower|T|t]][d|g]
          (Linear, log, and power scaling)

          Give x-scale (with  -Jx;  as  1:xxxx  or  plot-units/x-unit)  and/or
          y-scale  (1:xxxx  or  plot-units/y-unit);  or  specify  width and/or
          height (with -JX; in plot-units). 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.  Option-
          ally,  append to x-scale y-scale, width or height one of the follow-
          ing:

          o d to indicate that data are geographical coordinates (in degrees).

          o g to indicate that data are geographical coordinates

          o l to take log10 of values before scaling.

          o ppower to raise values to power before scaling.

          o t  to  indicate  that  input  coordinates  are  time  relative  to
            TIME_EPOCH.

          o T to indicate that input coordinates are absolute time.
                For mixed axes with only one geographic axis you may  need  to
                set -f as well.

       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.

       -Jproj|EPSG:n
              Starting  at  GMT6  it is possible to use the PROJ library to do
              coordinate and datum transforms.  This is achieved via  GDAL  so
              it  requires  that  GMT  build is linked to that library. It is,
              however, beyond the scope of this manual to  document  the  PROJ
              syntax  (that  is  the syntax of the proj and cs2cs programs) so
              users are referred to PROJ Applications for the details.

              The usage of PROJ follows very closely the syntax  of  proj  and
              cs2cs.  The  projection parameters are encapsulated under the -J
              option. Because there are normally several parameters defining a
              referencing  system separated by spaces (in PROJ or GDAL) we can
              either  use  double  quotes  as  in  -Ja+proj=merc  +ellps=WGS84
              +units=ma    or    just    glue    all    parameters   like   in
              -J+proj=merc+ellps=WGS84+units=m.

              Using EPSG codes is also possible (but need the setting  of  the
              GDAL_DATA  environment  variable  to  point  to  the GDALas data
              sub-directory). For example -JEPSG:4326 sets the WGS-84  system.

              For mapproject and grdproject we can go directly from the refer-
              encing system A to B without the intermediate step of converting
              to  geographic coordinates.  That is obtained (like in cs2cs) by
              using         the         +to         keyword.          Example:
              -JEPSG:4326+to+proj=aeqd+ellps=WGS84+units=m.   A  much  awaited
              bonus is also that we now do not need to  set  -R  to  do  point
              coordinate conversions.

              While for point and grid conversions done by mapproject and grd-
              project we can use all PROJ projections, the situations is, how-
              ever,  rather more limited for mapping purposes.  Here, only the
              subset of the PROJ projections that can be mapped into  the  GMT
              projections  syntax  is available to use. Another aspect that is
              not present in PROJ, because itas not a mapping library, is  how
              to  set  the  map  scale or map dimension. We introduced the two
              extensions +width=size and +scale=1:xxxx that work exactly  like
              the  map width and scale in classical GMT. It is also allowed to
              provide the scale (but NOT the width) by  appending  the  string
              a/1:xxxa to the end of the projection parameters.

   The -R option
       Syntax

       -Rxmin/xmax/ymin/ymax[+r][+uunit]
              Specify the region of interest. (See cookbook information).

       Description

       The -R option defines the map region or data domain of interest. It may
       be specified in one of seven ways (options 1 and 2 are shown in  panels
       a) and b) respectively of the Figure Map region):

       1. -Rxmin/xmax/ymin/ymax[+uunit].  This  is the standard way to specify
          Cartesian data domains and geographic regions when using map projec-
          tions  where  meridians  and  parallels are rectilinear. Optionally,
          append +uunit to specify a region  in  projected  units  (e.g.,  UTM
          meters)  where  xmin/xmax/ymin/ymax  are Cartesian projected coordi-
          nates compatible with the chosen projection and unit is an allowable
          distance unit.

       2. -Rxlleft/ylleft/xuright/yuright+r.  This form is useful for map pro-
          jections that are  oblique,  making  meridians  and  parallels  poor
          choices  for map boundaries. Here, we instead specify the lower left
          corner and upper right corner geographic  coordinates,  followed  by
          the  modifier +r. This form guarantees a rectangular map even though
          lines of equal longitude and latitude are not straight lines.

       3. -Rg or -Rd. These forms can be used to quickly  specify  the  global
          domain  (0/360  for  -Rg  and  -180/+180  for -Rd in longitude, with
          -90/+90 in latitude).

       4. -Rgridfile. This will copy the domain settings found for the grid in
          specified  file.  Note  that  depending on the nature of the calling
          module, this mechanism will also set grid spacing and  possibly  the
          grid   registration  (see  cookbook/options:Grid  registration:  The
          **-r** option).

       5. -Rcode1,code2,^<i>a|[+e|r|Rincs]]. This indirectly supplies  the  region
          by  consulting  the  DCW  (Digital  Chart of the World) database and
          derives the bounding regions for one or more countries given by  the
          codes. Simply append one or more comma-separated countries using the
          two-character ISO 3166-1 alpha-2  convention.   To  select  a  state
          within  a  country  (if  available),  append  .state, e.g, US.TX for
          Texas. To specify a whole continent, prepend = to any of the  conti-
          nent  codes AF (Africa), AN (Antarctica), AS (Asia), EU (Europe), OC
          (Oceania), NA (North America), or SA (South America). The  following
          modifiers can be appended:

          o +r  to  adjust  the region boundaries to be multiples of the steps
            indicated by inc, xinc/yinc, or winc/einc/sinc/ninc [default is no
            adjustment].  For example, -RFR+r1 will select the national bound-
            ing box of France rounded to nearest integer degree.

          o +R to extend the region outward by adding the amounts specified by
            inc,  xinc/yinc, or winc/einc/sinc/ninc [default is no extension].

          o +e to adjust the region boundaries to be multiples  of  the  steps
            indicated  by inc, xinc/yinc, or winc/einc/sinc/ninc, while ensur-
            ing that the bounding box extends  by  at  least  0.25  times  the
            increment [default is no adjustment].

       6. -Rjustifyx0/y0/nx/ny,  where justify 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). The two character code justify
          indicates which point on a rectangular grid region the x0/y0 coordi-
          nates  refer to and the grid dimensions nx and ny are used with grid
          spacings given via -I  to  create  the  corresponding  region.  This
          method can be used when creating grids. For example, -RCM25/25/50/50
          specifies a 50x50 grid centered on 25,25.

       7. -Rxmin/xmax/ymin/ymax/zmin/zmax. This method can be  used  for  per-
          spective  views  with  the  -Jz and the -p option, where the z-range
          (zmin/zmax) is appended to the first method to  indicate  the  third
          dimension. This is not used for -p without -Jz, in which case a per-
          spective view of the place is plotted with no third dimension
          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.

   The -U option
       Syntax

       -U[label|+c][+jjust][+odx/dy]
              Draw GMT time stamp logo on plot. (See cookbook information).

       Description

       The -U option draws the GMT system time stamp on the plot. The  follow-
       ing modifiers are supported:

       o label  to  append  the text string given in label (which must be sur-
         rounded by double quotes if it contains spaces).

       o +c to plot the current command string.

       o +jjustify to specify the justification of the time stamp, where  jus-
         tify is a two-character justification code that is a combination of a
         horizontal (L(eft), C(enter), or  R(ight))  and  a  vertical  (T(op),
         M(iddle), or B(ottom)) code [default is BL].

       o +odx[/dy]  to  offset  the  anchor point for the time stamp by dx and
         optionally dy (if different than dx).

       The  GMT  parameters  MAP_LOGO,  MAP_LOGO_POS,   FONT_LOGO   and   FOR-
       MAT_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  environ-
       ment variable TZ (generally local time).

   The -V option
       Syntax

       -V[level]
              Select verbosity level [w]. (See cookbook information).

       Description

       The  -V option controls the verbosity mode, which determines which mes-
       sages are sent to standard error. Choose among 7 levels  of  verbosity;
       each level adds more messages:

       o q - Quiet, not even fatal error messages are produced.

       o e - Error messages only.

       o w - Warnings.

       o t - Timings (report runtimes for time-intensive algorithms).

       o i - Informational messages (same as -V only).

       o c - Compatibility warnings (if compiled with backward-compatibility).

       o d - Debugging messages.

       This option can also be set by specifying the  default  GMT_VERBOSE  as
       quiet,  error, warning, timing, compat, information, or debug, in order
       of increased verbosity [default is warning].

   The -X -Y options
       Syntax

       -X[a|c|f|r][xshift]
              Shift plot origin. (See cookbook information).

       -Y[a|c|f|r][yshift]
              Shift plot origin. (See cookbook information).

       Description

       The -X and -Y options shift the plot origin  relative  to  the  current
       origin by (xshift,yshift). Optionally, append the length unit (c, i, or
       p). Default  is  (MAP_ORIGIN_X,  MAP_ORIGIN_Y)  for  new  plots,  which
       ensures  that boundary annotations fit on the page. Subsequent overlays
       will be co-registered with the  previous  plot  unless  the  origin  is
       shifted  using  these  options.  The  following modifiers are supported
       [default is r]:

       o Prepend a to shift the origin back to  the  original  position  after
         plotting.

       o Prepend  c  to center the plot on the center of the paper (optionally
         add a shift).

       o Prepend f to shift the origin relative to the fixed lower left.

       o Prepend r to move the origin relative to its current location.

       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.
       Note that -X and -Y can also access  the  previous  plot  bounding  box
       dimensions  w  and  h  and  construct  offsets that involves them.  For
       instance, to move the origin up 2 cm beyond the height of the  previous
       plot,  use  -Yh+2c. To move the origin half the width to the right, use
       -Xw/2.

   The -a option
       Syntax

       -a[[col=]name][,^<i>a|]
              Control how aspatial data are handled in GMT  during  input  and
              output.

       Description

       GMT  relies  on  external  tools  to translate geospatial files such as
       shapefiles into a format we can read. The  tool  ogr2ogr  in  the  GDAL
       package can do such translations and preserve the aspatial metadata via
       a new OGR/GMT format specification (See  the  cookbook  chapter  /cook-
       book/ogrgmt-format). For this to be useful we need a mechanism to asso-
       ciate certain metadata values with required input  and  output  columns
       expected  by  GMT  programs.  The -a option allows you to supply 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 as data input for column col. The given aspatial field thus replaces
       any  other  value  already set. Note: col = 0 is the first data column.
       Note: If no aspatial attributes are needed then the -a  option  is  not
       needed a GMT will still process and read such data files.

   OGR/GMT input with -a option
       If  you need to populate GMT data columns with (constant) values speci-
       fied by aspatial attributes, use -a and append any number of comma-sep-
       arated col=name associations. For example, -a2=depth will read the spa-
       tial x,y columns from the file and add a third (z) column based on  the
       value  of the aspatial field called depth. You can also associate aspa-
       tial fields with other settings such as labels, fill colors, pens,  and
       values  (for  looking-up  colors)  by letting the col value be one of D
       (for distance), G (for fill), I (for ID), L (for label), T (for  text),
       W  (for  pen), or Z (for value). This works analogously to how standard
       multi-segment files can pass such options via its segment headers  (See
       the cookbook chapter /cookbook/file-formats). Note: If the leading col=
       is omitted, the column value is automatically incremented  starting  at
       2.

   OGR/GMT output with -a option
       GMT  table-writing  tools  can also output the OGR/GMT format directly.
       Specify if certain GMT data columns  with  constant  values  should  be
       stored  as  aspatial  metadata  using  col=name[:type],  where  you can
       optionally specify what data type it should be from the options double,
       float,  integer,  char,  string, logical, byte, or datetime [default is
       double]. As for input, you can also use the special col  entries  of  D
       (for  distance), G (for fill), I (for ID), L (for label), T (for text),
       W (for pen), or Z (for value) to have values stored as options in  seg-
       ment  headers  be  used as the source for the named aspatial field. The
       type will be set automatically for these special col entries.  Finally,
       for  output  you  must  append +ggeometry, where geometry can be any of
       [M]POINT|LINE|POLY; where M  represents  the  multi-versions  of  these
       three  geometries.  Use  upper-case +G to signal that you want to split
       any line or polygon features that straddle the Dateline.

   The -bi option
       Syntax

       -bi[ncols][type][w][+l|b]
              Select native binary format for primary input (secondary  inputs
              are always ASCII).

       Description

       Select  native binary format for primary input, where ncols is the num-
       ber of data columns of given type and type must be one of:

          o c - int8_t (1-byte signed char)

          o u - uint8_t (1-byte unsigned char)

          o h - int16_t (2-byte signed int)

          o H - uint16_t (2-byte unsigned int)

          o i - int32_t (4-byte signed int)

          o I - uint32_t (4-byte unsigned int)

          o l - int64_t (8-byte signed int)

          o L - uint64_t (8-byte unsigned int)

          o f - 4-byte single-precision float

          o d - 8-byte double-precision float

          o x - use to skip ncols anywhere in the record

       For records with mixed types, simply append additional  comma-separated
       combinations of ncols type (no space). The following modifiers are sup-
       ported:

          o w after any item to force byte-swapping

          o +l|b to indicate that the entire data file should be read as  lit-
            tle- 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 pro-
       gram. When using native binary data the user must be aware of the  fact
       that  GMT has no way of determining the actual number of columns in the
       file. Native binary files may have  a  header  section,  where  the  -h
       option  can  be  used  to  skip the first n bytes. If the input file is
       netCDF, no -b is needed; simply append ?var1/var2/^<i>a| to the filename to
       specify  the variables to be read (see /cookbook/file-formats and Modi-
       fiers for COARDS-compliant netCDF files for more information).  Here is
       an  example  that writes a binary file and reads it back with the first
       column 4 byte float, the second column 8 byte int, and the third column
       8 byte double.

          echo 1.5 2 2.5 | gmt convert -bo1f,1l,1d > lixo.bin
          gmt convert lixo.bin -bi1f,1l,1d

   The -bo option
       Syntax

       -bo[ncols][type][w][+l|b]
              Select native binary output.

       Description

       Select  native binary output, where ncols is the number of data columns
       of type, which must be one of c, u, h, H, i, I, l, L, f, or d (see  -bi
       types  for descriptions).  For a mixed-type output record, append addi-
       tional comma-separated combinations of ncols type (no space). The  fol-
       lowing modifiers are supported:

          o w after any item to force byte-swapping

          o +l|b  to indicate that the entire data file should be read as lit-
            tle- or big-endian, respectively.

       If ncols is not specified we assume that type applies  to  all  columns
       and  that  ncols is implied by the default output of the program. Note:
       NetCDF file output is not supported.

   The -c option
       Syntax

       -c[row,col|index]
              Advance to the selected subplot panel.

       Description

       The -c option can be used to either advance the focus  of  plotting  to
       the  next  panel  in the sequence (either by row or by column as set by
       subplotas -A option) or to specify directly the row,col or 1-D index of
       the  desired panel, when using /subplot to assemble multiple individual
       panels in a matrix layout.  The -c option is only allowed when in  sub-
       plot  mode.   If  no  -c  option is given for the first subplot then we
       default to row=col=index=0, i.e., the upper  left  panel.   Note:  row,
       col, and index all start at 0.

   The -d option
       Syntax

       -di|onodata
              Substitute specific values with NaN.

       Description

       The -d option allows user-coded missing data values to be translated to
       official NaN values in GMT. Within GMT, any missing values  are  repre-
       sented  by  the  IEEE  NaN  value.  However, user data may occasionally
       denote missing data with an unlikely value (e.g.,  -99999).  Since  GMT
       cannot guess this special missing data value, you can use the -d option
       to have such values replaced with NaNs. Similarly, the  -d  option  can
       replace  all  NaNs  with  the chosed nodata value should the GMT output
       need to conform to such a requirement.

       For input only, use -dinodata to examine all input columns. If any item
       equals  nodata,  the value is interpreted as a missing data item and is
       substituted with the value NaN.

       For output only, use -donodata to examine all output  columns.  If  any
       item  equals  NaN, the NaN value is substituted with the chosen missing
       data value nodata.

   The -e option
       Syntax

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i]
              Only accept ASCII data records that contain the  specified  pat-
              tern.

       Description

       The  -e  option  offers  a built-in pattern scanner that will only pass
       records that match the given pattern or  regular  expressions,  whereas
       modules  that  read  ASCII  tables  will  normally process all the data
       records that are read.  The test can also be inverted to only pass data
       records  that  do  not match the pattern, by using -e~. The test is not
       applied to header or segment headers. Should  your  pattern  happen  to
       start  with  ~  you will need to escape this character with a backslash
       [Default accepts all data records]. For matching data  records  against
       extended regular expressions, please enclose the expression in slashes.
       Append i for case-insensitive matching. To supply a list of  such  pat-
       terns, give +ffile with one pattern per line.  To give a single pattern
       starting with +f, escape it with a backslash.

   The -f option
       Syntax

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

       Description

       The  -f  option specifies what kind of data each input or output column
       contains when map projections are not required. Optionally, append i or
       o  to  make  this  apply only to input or output, respectively [Default
       applies to both]. Append a text string with information about each col-
       umn  (or range of columns) separated by commas. Each string starts with
       the column number (0 is the first column) followed by either x  (longi-
       tude),  y (latitude), T (absolute calendar time) or t (relative time in
       chosen TIME_UNIT since TIME_EPOCH). If several consecutive columns have
       the same format you may specify a range of columns rather than a single
       column. Column ranges must be given  in  the  format  start[:inc]:stop,
       where  inc  defaults  to 1 if not specified.  For example, if our input
       file has geographic coordinates  (latitude,  longitude)  with  absolute
       calendar  coordinates  in  the  columns  3  and  4,  we  would  specify
       fi0y,1x,3:4T. All other columns are assumed to have the default (float-
       ing point) format and need not be set individually.

       The  shorthand  -f[i|o]g  means  -f[i|o]0x,1y (i.e., geographic coordi-
       nates). A special use of -f is to select -fp[unit], which  requires  -J
       and  lets  you use projected map coordinates (e.g., UTM meters) as data
       input. Such coordinates are automatically inverted to longitude,  lati-
       tude  during the data import. Optionally, append a length unit (see ta-
       ble distance units) [default is meter]. For more information, see  Sec-
       tions input-data-formats and output-data-formats.

   The -g option
       Syntax

       -g[a]x|y|d|X|Y|D|[col]zgap[+n|p]
              Examine  the spacing between consecutive data points in order to
              impose breaks in the line.

       Description

       The -g option is used to detect gaps based on  one  or  more  criteria.
       Repeat  the option to specify multiple criteria and prepend a to subse-
       quent modifiers to specify that all the criteria must be  met  [default
       imposes  breaks  if any one criteria is met]. The criteria is specified
       using the x|y|d|X|Y|D|[col]z modifiers. The upper-case options  specify
       that  the  criteria  should be applied to the projected coordinates for
       modules that map data to map coordinates.

       o x|X - define a gap when there is a large enough change in the x coor-
         dinates (upper case to use projected coordinates).

       o y|Y - define a gap when there is a large enough change in the y coor-
         dinates (upper case to use projected coordinates).

       o d|D - define a gap when there is  a  large  enough  distance  between
         coordinates (upper case to use projected coordinates).

       o [col]z - define a gap when there is a large enough change in the data
         in column col [default col is 2 (i.e., 3rd column)].

       A unit u may be appended to the specified gap:

       o For geographic data (x|y|d), the unit may be arc d(egree),  m(inute),
         and  s(econd), or (m)e(ter), f(eet), k(ilometer), M(iles), or n(auti-
         cal miles) [Default is (m)e(ter)].

       o For projected data (X|Y|D), the unit may be i(nch), c(entimeter),  or
         p(oint) [Default unit is set by PROJ_LENGTH_UNIT].

       One  of the following modifiers can be appended to gap [default imposes
       breaks based on the absolute value of the difference between  the  cur-
       rent and previous value]:

       o +n  -  specify that the previous value minus the current column value
         must exceed gap for a break to be imposed.

       o +p - specify that the current value minus  the  previous  value  must
         exceed gap for a break to be imposed.

       Note:  For  x|y|z  with  time  data  the  unit is instead controlled by
       TIME_UNIT. Note: GMT has other mechanisms that can determine line  seg-
       mentation,  including  segments  defined  by  multiple  segment  header
       records (see the cookbook chapter /cookbook/file-formats)  or  segments
       defined by NaN values when IO_NAN_RECORDS is set to pass [default skips
       NaN values].

   The -h option
       Syntax

       -h[i|o][n][+c][+d][+msegheader][+rremark][+ttitle]
              Specify that input and/or output file(s) have n  header  records
              [default is 0].

       Description

       Specify  that  the  primary  input  file(s) has n header record(s). The
       default number of header records is set by IO_N_HEADER_RECS [default is
       0].  Use  -hi if only the primary input data should have header records
       [Default will write out header records if the input  data  have  them].
       For  output  you  may control the writing of header records using -h[o]
       and the optional modifiers:

       o +d to remove existing header records.

       o +c to add a header comment with column names to the  output  [default
         is no column names].

       o +m  to  add a segment header segheader to the output after the header
         block [default is no segment header].

       o +r to add a remark comment to the output [default is no comment]. The
         remark string may contain \n to indicate line-breaks.

       o +t  to  add  a title comment to the output [default is no title]. The
         title string may contain \n to indicate line-breaks.

       Note: Blank lines and lines starting with # are always skipped. To  use
       another   leading   character   for   indicating  header  records,  set
       IO_HEADER_MARKER. With -h in effect the first n records are taken  ver-
       batim  as headers and not skipped even if any is starting with #. Note:
       If used with native binary data (using -b) we interpret  n  to  instead
       mean the number of bytes to skip on input or pad on output.

   The -i option
       Syntax

       -icols[+l][+ddivisor][+sscale][+ooffset][,^<i>a|][,t[word]]
              Select  specific  data  columns  for primary input, in arbitrary
              order.

       Description

       The -i option allows you to specify which input file physical data col-
       umns  to  use  and  in what order. Specify individual columns 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  (i.e.,  column  0)].  Columns  can  be
       repeated. The chosen data columns will be used as given and columns not
       listed will be skipped. Optionally, append one of the  following  modi-
       fiers to any column or column range to transform the input columns:

       o +l to take the log10 of the input values.

       o +d to divide the input values by the factor divisor [default is 1].

       o +s to multiply the input values by the factor scale [default is 1].

       o +o to add the given offset to the input values [default is 0].

       To read from a given column until the end of the record, leave off stop
       when specifying the column range. Normally, any trailing text  is  read
       but  when -i is used you must explicitly add the column t to retain the
       text. To only ingest a single word from the trailing text,  append  the
       word  number  (first  word  is  0).   Finally, -in will simply read the
       numerical input and skip any trailing text.

   The -j option (spherical distance calculations)
       Syntax

       -je|f|g
              Determine how spherical distances are calculated in modules that
              support this [Default is -jg].

       Description

       GMT has different ways to compute distances on planetary bodies:

       o -jg  to  perform  great circle distance calculations, with parameters
         such as distance increments  or  radii  compared  against  calculated
         great circle distances [Default is -jg].

       o -jf  to  select  Flat  Earth mode, which gives a more approximate but
         faster result.

       o -je to select ellipsoidal (or geodesic) mode for the  highest  preci-
         sion and slowest calculation time.

       Note:  All spherical distance calculations depend on the current ellip-
       soid   (PROJ_ELLIPSOID),   the   definition   of   the   mean    radius
       (PROJ_MEAN_RADIUS),    and   the   specification   of   latitude   type
       (PROJ_AUX_LATITUDE).  Geodesic distance calculations is also controlled
       by method (PROJ_GEODESIC).

   The -l option
       Syntax

       -l[label][+Dpen][+Ggap][+Hheader][+L[code/]text][+Ncols][+Ssize[/height]][+V[pen]][+ffont][+gfill][+jjus-
       tify][+ooff][+ppen][+sscale][+wwidth]
          Add a map legend entry to the session legend  information  file  for
          the current plot.

       Description

       The  -l option is used to automatically build the specfile that is read
       by the /legend module to  create  map  or  plot  legends.  This  allows
       detailed  and  complicated legends that mix a variety of items, such as
       symbols, free text, colorbars, scales, images, and more. Yet, a  simple
       legend  will  suffice for the vast majority of plots displaying symbols
       or lines. Optionally, append a text label to describe  the  entry.  The
       following  modifiers are supported to allow further changes to the leg-
       end that is built by /legend (upper-case modifiers reflect legend codes
       described in /legend, which provides more details and customization):

       o +D to draw a horizontal line in the given pen before the legend entry
         is placed [default is no line].

       o +G to add the vertical space specified by gap [default  is  no  extra
         space].

       o +H to add the specified legend header [default is no header].

       o +L to set a line text. Optionally, prepend a horizontal justification
         code L(eft), C(enter), or R(ight) for text [default is C].

       o +N to change the number of columns used to set the  following  legend
         items to cols [default is 1].

       o +S to override the size of the current symbol for the legend or set a
         height if plotting a line or contour [default uses the same symbol as
         plotted].

       o +V  to start and +vpen to stop drawing vertical line from previous to
         current horizontal line [default is no vertical line].

       o +f  to  set  the  font  used  for  the  legend  header  [default   is
         FONT_TITLE].

       o +g to set the fill used for the legend frame [default is white].

       o +j  to set placement of the legend using the two-character justifica-
         tion code justify [default is TR].

       o +o to set the offset from legend frame to anchor  point  [default  is
         0.2c].

       o +p to set the pen used for the legend frame [default is 1p].

       o +s  to  resize  all  symbol  and  length sizes in the legend by scale
         [default is no scaling].

       o +w to set legend frame width [default is auto].

       Note: Default pen is given by MAP_DEFAULT_PEN. Note: +H,  +g,  +j,  +o,
       +p,  +w,  and +s will only take effect if appended to the very first -l
       option for a plot. The +N modifier, if appended to the first -l option,
       affects  the legend width (unless set via +w); otherwise it just subdi-
       vides the available width among the specified columns. If legend is not
       called  explicitly  we  will call it implicitly when finishing the plot
       via /end. Note: If auto-coloring is used for pens or fills  and  -l  is
       set  then  label  may  contain a C-format for integers (e.g., %3.3d) or
       just # and we will use the sequence number with the format to build the
       label  entries.   Alternatively, give a list of comma-separated labels,
       or give no label if your segment headers contain label settings.

   The -n option
       Syntax

       -n[b|c|l|n][+a][+bg|p|n][+c][+tthreshold]
              Select grid interpolation mode.

       Description

       The -n  option  controls  parameters  used  for  2-D  grids  resampling
       [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]. Append one of the following to select the type of
       spline used:

       o b to use B-spline smoothing.

       o c to use bicubic interpolation.

       o l to use bilinear interpolation.

       o n to use nearest-neighbor value  (for  example  to  plot  categorical
         data).

       The following modifiers are supported:

       o +a  to  switch  off  antialiasing  (where  supported)  [default  uses
         antialiasing].

       o +b to override boundary conditions used,  by  appending  g  for  geo-
         graphic,  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.

       o +c  to  clip  the interpolated grid to input z-min/z-max [default may
         exceed limits].

       o +t to control how close to nodes with NaNs the interpolation will  go
         based  on  threshold. A threshold of 1.0 requires all (4 or 16) nodes
         involved in interpolation to be non-NaN. For example, 0.5 will inter-
         polate  about half way from a non-NaN value and 0.1 will go about 90%
         of the way [default is 0.5].

   The -o option
       Syntax

       -ocols[,a|][,t[word]]
              Select specific data columns for primary  output,  in  arbitrary
              order.

       Description

       The  -o  option  allows  you to specify which output file physical data
       columns to use and in what order. Specify individual columns or  column
       ranges  in  the format start[:inc]:stop, where inc defaults to 1 if not
       specified, separated by commas [Default writes all  columns  in  order,
       starting  with  the  first  column  (i.e.,  column  0)]. Columns can be
       repeated. The chosen data columns will be used as given and columns not
       listed  will  be skipped. To write from a given column until the end of
       the record, leave off stop when specifying the column range.

       Normally, any trailing text in the internal records will be written but
       when  -o is used you must explicitly add the column t. To only output a
       single word from the trailing text, append the word number (first  word
       is  0).   Finally,  -on will simply write the numerical output only and
       skip any trailing text, while -ot will only output  the  trailing  text
       (or  selected  word). Note: If -i is also used then columns given to -o
       correspond to the order after the -i selection and not the  columns  in
       the original record.

   The -p option
       Syntax

       -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0]
              Select perspective view and set the azimuth and elevation of the
              viewpoint.

       Description

       All plotting programs that normally  produce  a  flat,  two-dimensional
       illustration can be told to view this flat illustration from a particu-
       lar vantage point, resulting in a perspective view. You can select per-
       spective  view  with the -p option by setting the azimuth (azim) of the
       viewpoint [Default is 180]. The following modifiers are supported:

       o x|y|z to plot against the awalla x = level (using x)  or  y  =  level
         (using y) or the horizontal plain (using z) [default is z].

       o /elev to set the elevation of the viewport [Default is 90].

       o /zlevel  to  indicate  the z-level at which all 2D material, like the
         plot frame, is plotted (only valid when -p is used  in  consort  with
         -Jz or -JZ) [Default is at the bottom of the z-axis].

       For  frames  used for animation, we fix the center of your data domain.
       Specify another center using one of the following modifiers:

       o +w to project lon0/lat0 (and z0 if applicable) to the center  of  the
         page size.

       o +v  to  specify  the  coordinates  of the projected 2-D view point as
         x0/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 (in modern mode this
       also supplies the previous -Jz or -JZ if doing a 3-D region).  Alterna-
       tively, you can perform a simple rotation about the z-axis by just giv-
       ing the rotation angle. Optionally, use +v or +w to select another axis
       location than the plot origin.

   The -q option
       Syntax

       -q[i|o][~]rows[+ccol][+a|f|s]
              Select specific data rows to be read and/or written.

       Description

       The -q option is used to select specific data rows to be read (using -q
       or -qi) or written (using -qo) [Default is all rows]. Specify  individ-
       ual  rows  or  row  ranges  in  the  format start[:inc]:stop, where inc
       defaults to 1 if not specified, separated by commas [Default reads  and
       writes  all  rows in order, starting with the first row (i.e., row 0)].
       To read (or write) from a given row until the end of  the  data,  leave
       off  stop.  To  select  all the rows not specified by the given ranges,
       prepend the selected rows with a leading ~. Append one of the following
       modifiers to control how the rows are counted [Default is +a]:

       o +a to count all rows in the data set.

       o +f to reset the count at the start of each file.

       o +s to reset the count at the start of each segment.

       Alternatively,  use  +ccol  to  indicate that the arguments instead are
       min/max data limits for the values in column col. With +ccol, only rows
       whose  data  for  the given column col are within the range(s) given by
       the min/max limits are read (with -qi) or  written  (with  -qo).  Note:
       Because  arguments may contain colons or be negative, your must specify
       start/stop instead of start[:inc]:stop.

       Note: Header records do  not  increase  the  row  counters;  only  data
       records do.

   The -r option (grid registration)
       Syntax

       -r[g|p]
              Select gridline or pixel node registration.

       Description

       All  2-D  grids  in  GMT have their nodes organized in one of two ways,
       known as gridline and pixel registration. The GMT default  is  gridline
       registration  (-rg);  programs that allow for the creation of grids can
       use the -r option (or -rp) to select pixel registration instead.

       Most observed data tend to be in gridline registration while  processed
       data  sometime may be distributed in pixel registration.  While you may
       convert between  the  two  registrations  this  conversion  looses  the
       Nyquist frequency and dampens the other high frequencies. It is best to
       avoid any registration conversion if you can help  it.  Planning  ahead
       may   be   important.   (Node  registrations  are  defined  in  Section
       option_nodereg of the GMT Technical Reference and Cookbook.)

   The -s option
       Syntax

       -s[cols][+a][+r]
              Suppress output of data records whose z-value(s) equal NaN.

       Description

       The -s option can be used to suppress output for records whose  z-value
       equals  NaN  [default  outputs  all  records].   Optionally,  supply  a
       comma-separated list of all columns or column ranges  to  consider  for
       this NaN test [default only considers the third data column (i.e., cols
       = 2)]. Column ranges must be  given  in  the  format  start[:inc]:stop,
       where  inc  defaults to 1 if not specified. The following modifiers are
       supported:

       o +r to reverse the suppression, i.e., only output  the  records  whose
         z-value equals NaN.

       o +a  to  suppress  the output of the record if just one or more of the
         columns equal NaN [default skips record only if values in all  speci-
         fied cols equal NaN]

   The -t option
       Syntax

       -ttransp[/transp2][+f|s]
              Set transparency level(s) for an overlay.

       Description

       The  -t option allows you to change the transparency level for the cur-
       rent overlay by appending the transp  percentage  in  the  0-100  range
       [default  is  0  (i.e., opaque)]. Normally, transp applies to both fill
       and stroke, but you can limit  the  transparency  to  one  of  them  by
       appending  +f  or  +s  for fill or stroke, respectively. Alternatively,
       append /transp2 to set separate transparencies for fills and strokes.

       Transparency may also be controlled on a feature by feature basis  when
       setting  color  or fill (see the cookbook section -Gfill_attrib). Note:
       The modules /plot, /plot3d, and /text can all change transparency on  a
       record-by-record  basis  if  -t is given without argument and the input
       file supplies variable transparencies  as  the  last  numerical  column
       value(s).  Note:  The  transparency  is only visible when PDF or raster
       format output is selected because the PostScript language does not sup-
       port  transparency.  Only  the PNG format selection adds a transparency
       layer in the image (for further processing).

   The -w option
       Syntax

       -wy|a|w|d|h|m|s|cperiod[/phase][+ccol]
              Convert input records to a cyclical coordinate.

       Description

       The -w option converts the input x-coordinate to a cyclical coordinate,
       or  a  different input column if selected via the +c modifier. Temporal
       data (i.e., regular time series) can be analyzed for periods via  stan-
       dard  spectral  analysis,  such  as offered by /spectrum1d and /grdfft.
       However, it is often of interest to examine aspects of such  periodici-
       ties  in  the  time domain.  To enable such analyses we need to convert
       our monotonically increasing time coordinates  to  periodic  or  cyclic
       coordinates  so that data from many cycles can be stacked, binned, dis-
       played in histograms, etc. The conversion from input x, y, or z coordi-
       nates to wrapped, periodic coordinates follows the simple equation

                         t' = (t - \tau) \;\mathrm{mod}\; T,

       where  t  is  the  input  coordinate,  \tau is a phase-shift (typically
       zero), and T is the desired period for the modulus  operator,  yielding
       cyclic  coordinates  t'.  GMT  offers many standard time cycles in pre-
       scribed units plus a custom cycle for other types of Cartesian  coordi-
       nates.  The  table  below  shows the values for units, phase and period
       that are prescribed and only requires the user to  specify  the  corre-
       sponding wrapping code (y|a|w|d|h|m|s|cperiod):

                  +-----+---------------+----------+-------+-------+
                  |Code | Purpose       | Period   | Phase | Range |
                  |     | (unit)        |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |y    | Yearly  cycle | 1 year   | 0     | 0a1   |
                  |     | (normalized)  |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |a    | Annual  cycle | 1 year   | 0     | 0a12  |
                  |     | (month)       |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |w    | Weekly  cycle | 1 week   | 0     | 0a7   |
                  |     | (day)         |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |d    | Daily   cycle | 1 day    | 0     | 0a24  |
                  |     | (hour)        |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |h    | Hourly  cycle | 1 hour   | 0     | 0a60  |
                  |     | (minute)      |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |m    | Minute  cycle | 1 minute | 0     | 0a60  |
                  |     | (second)      |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |s    | Second  cycle | 1 second | 0     | 0a1   |
                  |     | (second)      |          |       |       |
                  +-----+---------------+----------+-------+-------+
                  |c    | Custom  cycle | T        | \tau  | 0a1   |
                  |     | (normalized)  |          |       |       |
                  +-----+---------------+----------+-------+-------+

       Optionally, append +ccol to select the input column  with  the  coordi-
       nates  to  be  wrapped, [default col is 0 (i.e., the first column)]. If
       the custom cycle c is chosen then you must also supply the  period  and
       optionally  any  phase  [default  is  0] in the same units of your data
       (i.e., no units should be appended to -w).

       Note: Coordinates for w in the range 0-1 correspond to the first day of
       the  week  [Monday]  but can be changed via TIME_WEEK_START. Note: If a
       temporal cycle is indicated then we implicitly set -f to indicate abso-
       lute  time  (unless  already  set separately). See the cookbook section
       Examining data cycles: The -w option for examples.

   The -x option
       Syntax

       -x[[-]n]
              Specify  the  number  of  active  cores  to  be  used   in   any
              OpenMP-enabled multi-threaded algorithms.

       Description

       The   -x  option  limits  the  number  of  cores  to  be  used  in  any
       OpenMP-enabled multi-threaded algorithms [default is 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, with the exception of /movie and /batch which handle their own
       parallel execution.

   The -: option
       Syntax

       -:[i|o]
              Swap 1st and 2nd column on input and/or output.

       Description The -: option swaps the 1st and 2nd  column  on  input  and
       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  cook-
       book/options:Input columns selection: The **-i** option. Note that com-
       mand  line  arguments  that  may take geographic coordinates (e.g., -R)
       always expect longitude before latitude. Also, geographical  grids  are
       expected to have the longitude as first (minor) dimension.

   Module help and configuration
       -^ or just -
              Print a short message about the syntax of the command, then exit
              (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 exit.

       -? or no arguments
              Print a complete usage (help) message, including the explanation
              of all options, then exit.

       --PAR=value
              Temporarily  override  a  GMT  default  setting; repeatable. See
              /gmt.conf for parameters.

   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 triplet RGB (r/g/b, each in the range  0a255),  by
              hue-saturation-value  HSV  (h-s-v,  with  ranges  of 0-360, 0-1,
              0-1), by cyan/magenta/yellow/black CMYK (c/m/y/k,  each  in  the
              range  0-1), or by a hexadecimal color code (#rrggbb, as used in
              HTML). For a transparency effect, append  @transparency  in  the
              0a100  percent  range [Default is 0 (opaque)] Note: Transparency
              effects are only visible when PDF or a raster graphics format is
              selected.  See Explanation of color codes in GMT for more infor-
              mation 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
              [300].  For  1-bit rasters: use upper case P  for inverse video,
              or append +fcolor and/or +bcolor to specify fore- and background
              colors  (no color given means transparency).  See /cookbook/pre-
              defined-patterns for information  on  individual  built-in  pat-
              terns.

   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 =~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 (plus 4 optional Japanese 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

              35.  Ryumin-Light-EUC-H

              36.  Ryumin-Light-EUC-V

              37.  GothicBBB-Medium-EUC-H

              38.  GothicBBB-Medium-EUC-V

   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 wide.
              color specifies a gray shade  or  color  (see  Specifying  Color
              above).  style  can be any of asolida, adasheda adotteda, adash-
              dota, or adotdasha, 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  grids  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][+sscale][+ooff-
       set][+ninvalid], where id is a two-letter identifier of the  grid  type
       and  precision,  and the scale, offset and invalid are the arguments of
       optional modifiers to be applied to all grid values,  Here, invalid  is
       the  value  used  to  indicate missing data. In case the id is not pro-
       vided, as in +sscale, then 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 Reference 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 it 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 slices of
       3-, 4-, or 5-dimensional grids.

       When writing a netCDF file, the grid is  stored  by  default  with  the
       variable  name  aza.  To  specify another variable name varname, append
       ?varname to the file name. 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.


CLASSIC MODE OPTIONS

       These  options  are  only used in classic mode and are listed here just
       for reference.

       -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].


MORE INFORMATION SOURCES

       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 documentation site
       https://docs.generic-mapping-tools.org/


SEE ALSO

       docs


COPYRIGHT

       2021, The GMT Team.



6.2                              Jun 04, 2021                           gmt(1)

gmt 6.2.0 - Generated Wed Jun 9 13:35:24 CDT 2021
© manpagez.com 2000-2021
Individual documents may contain additional copyright information.