character (Unicode code point #x210F) directly.
This document deals with gnuplot version 4.2 which is the
latest official release as of March 2007.
Its version is
$Revision: 1.32 $, dated
$Date: 2007/03/12 17:43:14 $.
The newest version of this document is on the web at http://www.gnuplot.info/faq/.
This document was/is posted sometimes to the newsgroups ~comp.graphics.apps.gnuplot.
Send comments, suggestions etc via email to the developer mailing list
gnuplot-beta@lists.sourceforge.net.
Please contribute your suggestions with respect to the file faq.tex
available from http://cvs.sourceforge.net/viewcvs.py/gnuplot/faq/.
gnuplot is a command-driven interactive function plotting program. It can be used to plot functions and data points in both two- and three-dimensional plots in many different formats. It is designed primarily for the visual display of scientific data. gnuplot is copyrighted, but freely distributable; you don't have to pay for it.
The authors of gnuplot are: Thomas Williams, Colin Kelley, Russell Lang, Dave Kotz, John Campbell, Gershon Elber, Alexander Woo and many others.
The following quote comes from Thomas Williams:
I was taking a differential equation class and Colin was taking Electromagnetics, we both thought it'd be helpful to visualize the mathematics behind them. We were both working as sys admin for an EE VLSI lab, so we had the graphics terminals and the time to do some coding. The posting was better received than we expected, and prompted us to add some, albeit lame, support for file data.
Any reference to GNUplot is incorrect. The real name of the program is "gnuplot". You see people use "Gnuplot" quite a bit because many of us have an aversion to starting a sentence with a lower case letter, even in the case of proper nouns and titles. gnuplot is not related to the GNU project or the FSF in any but the most peripheral sense. Our software was designed completely independently and the name "gnuplot" was actually a compromise. I wanted to call it "llamaplot" and Colin wanted to call it "nplot." We agreed that "newplot" was acceptable but, we then discovered that there was an absolutely ghastly pascal program of that name that the Computer Science Dept. occasionally used. I decided that "gnuplot" would make a nice pun and after a fashion Colin agreed.
Yes. Gnuplot can read in files containing additional commands during an interactive session, or it can be run in batch mode by piping a pre-existing file or a stream of commands to stdin. Gnuplot is used as a back-end graphics driver by such higher-level mathematical packages as Octave, and can easily be wrapped in a cgi script for use as a web-driven plot generator.
Gnuplot is available for a number of platforms. These are: Unix (X11 and NeXTSTEP), Linux, VMS, OS/2, MS-DOS, Amiga, MS-Windows, OS-9/68k, Atari ST, BeOS, and Macintosh.
Please notify the FAQ-maintainer of any further ports you might be aware of.
You should be able to compile the gnuplot source more or less out of the box on any reasonable standard (ANSI/ISO C, POSIX) environment.
Gnuplot is freeware authored by a collection of volunteers, who cannot make any legal statement about the compliance or non-compliance of gnuplot or its uses. There is also no warranty whatsoever. Use at your own risk.
Citing from the README of a mathematical subroutine package by R. Freund:
For all intent and purpose, any description of what the codes are doing should be construed as being a note of what we thought the codes did on our machine on a particular Tuesday of last year. If you're really lucky, they might do the same for you someday. Then again, do you really feel *that* lucky?
Gnuplot is neither written nor maintained by the FSF. It is not covered by the General Public License, either. It used to be distributed by the FSF, however, due to licensing issues it is no longer.
Gnuplot is freeware in the sense that you don't have to pay for it. However it is not freeware in the sense that you would be allowed to distribute a modified version of your gnuplot freely. Please read and accept the Copyright file in your distribution.
See the main gnuplot web page http://www.gnuplot.info and references therein, mainly gnuplot links http://gnuplot.sourceforge.net/links.html.
Some documentation and tutorials are available in other languages than English. See http://gnuplot.sourceforge.net/help.html, section "Localized learning pages about gnuplot", for the most up-to-date list.
The current released version of gnuplot is 4.2.
The best place is definitely http://www.gnuplot.info. From there you find various pointers to other sites.
The source distribution ("gnuplot-4.2.0.tar.gz" or a similar name) is available from the official distribution site and its mirrors.
The main server is ftp.gnuplot.info in /pub/gnuplot/. This server is mirrored by several others, among those are
As of June 1999, the gnuplot distribution is also mirrored at the Comprehensive TeX Archive Network (CTAN) in the graphics/gnuplot directory. See
The following platform-specific sites below still exist, but may or may not still hold gnuplot executables.
The development version of gnuplot is availble as a cvs source tree online for direct browsing from http://www.sourceforge.net/projects/gnuplot/, section "CVS". You can download all current sources according to the documentation therein; for example by a sequence of commands like
cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/gnuplot login cvs -z3 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/gnuplot co -P gnuplotor (in bash)
export CVSROOT=:pserver:anonymous@cvs.sourceforge.net:/cvsroot/gnuplot cvs login cvs -z3 checkout gnuplot
Further, before the ./configure command of gnuplot compilation phase, you have to execute ./prepare to create the up-to-date configure files.
There are no official preliminary binary releases of gnuplot: you have to compile it yourself. However, you may find unofficial binary releases for some platforms, like OS/2, Windows or Macintosh.
Important note: questions related to the development version should go to gnuplot-beta@lists.sourceforge.net.
As you would any other installation. Read the files README.1ST and README.
The documentation is included in the source distribution. Look at the docs subdirectory, where you'll find
The documentation is built during installation if you have LATEX installed on your system, look in the directories docs and tutorial. make pdf in the docs subdirectory will make a gnuplot.pdf hypertext file ready for browsing or printing.
Online gnuplot documentation is available at http://gnuplot.sourceforge.net/documentation.html.
(Obsolete?) PostScript copies of the documentation can be ftp'd from ftp.gnuplot.info in /pub/gnuplot, as manual.ps.Z and tutorial.ps.Z. Documentation about gnuplot is available at the gnuplot distribution sites in the files gpdoc.zip and gpdoc2.zip.
There is a directory of worked examples in the the source distribution. These examples, and the resulting plots, may also be found at http://gnuplot.sourceforge.net/demo/.
For this, you will need to recompile gnuplot.
Modifications people make are either done by replacing files, such as terminal drivers, or by 'patching'. If a file is a replacement, it will probably tell you in its README or in the lines at the beginning.
To patch a file, you need the patch utility, and possibly
also automake and autoconf. On many UNIX systems
these will already be installed; If they aren't, you can find
them wherever GNU software is archived. Typical command for applying a patch
is patch -p0 <newfunctionality.diff.
There is repository of contributed patches in the "Patches" section on gnuplot's sourceforge site http://www.sourceforge.net/projects/gnuplot/.
Read this document.
Give the help command at the initial prompt. After that, keep
looking through the keywords. Good starting points are plot
and set.
Read the manual, if you have it.
Look through the demo subdirectory; it should give you some ideas.
Ask your colleagues, the system administrator or the person who set up gnuplot.
If all these fail, please upgrade to the newest version of gnuplot
or urge your system-administrator to do so. Then
post a question to ~comp.graphics.apps.gnuplot
or send mail
to the gatewayed mailing list gnuplot-info@lists.sourceforge.net.
Do not forget to cite the version number and the operating system.
If you want to subscribe to the mailing list, send a mail to
majordomo@lists.sourceforge.net
with the body of the message being
subscribe info-gnuplot. Please don't do this if you can get
~comp.graphics.apps.gnuplot
directly. If you post a
question there, it is considered good form to solicit e-mail
replies and post a summary.
The kind of output produced is determined by the set terminal
command; for example, set terminal postscript will produce
the graph in PostScript format. Output can be redirected using
the set output command.
As an example, the following prints out a graph of sin(x) on a Unix machine running the X-Window System.
gnuplot> plot [-6:6] sin(x) gnuplot> set terminal postscript Terminal type set to 'postscript' Options are 'landscape monochrome "Courier" 14' gnuplot> set output "sin.ps" gnuplot> replot gnuplot> set output # set output back to default gnuplot> set terminal x11 # ditto for terminal type gnuplot> ! lp -ops sin.ps # print PS File (site dependent) request id is lprint-3433 (standard input) lp: printed file sin.ps on fg20.rz.uni-karlsruhe.de (5068 Byte) ! gnuplot>
Using the platform-independent way of restoring terminal by set term push/pop commands, do it by
gnuplot> set terminal postscript eps color lw 15 "Helvetica" 20 gnuplot> set out 'a.eps' gnuplot> replot gnuplot> set term popThe command set term pop without a previous corresponding set term push switches the terminal back to the startup terminal, e.g. x11, pm or win.
In Microschrott Windows you click in the upper left corner of the graph window and print directly from there.
Basically, you save your plot to a file in a format your word
processor can understand (using set term and set output,
see above), and then you read in the plot from your word processor. Vector
formats (PostScript, emf, svg, pdf, TEX, LATEX, etc) should be preferred,
as you can scale your graph later to the right size.
Details depend on which word processor you use; use set term to get a
list of available file formats.
Many word processors can use Encapsulated PostScript for graphs.
This can be generated by the
set terminal postscript eps [color]
command.
Note that it is a good idea to check and correct the bounding box of the
graphs in the eps files (manually or by the fixbb script from gnuplot
webpage), as you have to correct this box for any eps figure produced by
whichever program.
Some (most?) word processors do not preview the actual image in the eps
file, and you have to add the preview image yourself. You can use the GSView
viewer for this (available for OS/2, Windows and X11), or some Unix ps
tool. Note that the preview image increases size of the eps file; the
smallest increase you may get by choosing Tiff 6 Packbits.
Some office Windows applications, also OpenOffice.org, can handle vector images produces by the emf terminal. OpenOffice.org can also read AutoCAD's dxf format, as well as SVG thanks to SVG Import Filter http://www.ipd.uni-karlsruhe.de/ hauma/svg-import/.
With TEX, it depends on what you use to print your dvi files. If you use dvips or dvi2ps, you can use Encapsulated PostScript. For emTeX (popular for OS/2 and MS-DOS), you can use emTeX, otherwise use the LATEX terminal type, which generates a picture environment. You can also use epslatex to separate the graphics and text parts. Other possibilities include pslatex or pstex terminals, and metafont or metapost terminals.
With TEX processed by pdftex or pdflatex, you can use png, jpeg and pdf
terminal types. You can also use the postscript eps terminal and convert the eps
file externally to pdf by epstopdf. Another choice is the epslatex
terminal, after converting the eps part to pdf as above (the TEX part can
remain unchanged).
Most word processors can import bitmap images (png, pbm, etc). The disadvantage of this approach is that the resolution of your plot is limited by the size of the plot at the time it is generated by gnuplot, which is generally a much lower resolution than the document will eventually be printed in.
Under IBM OS/2, MacOS and Micro$oft Windows you can use the clipboard to copy your graph and paste it into your favourite word processor.
The mif terminal type produces output for FrameMaker.
This depends on the terminal type you use.
You may use the tgif terminal, which creates output suitable for reading within tgif (http://bourbon.cs.umd.edu:8001/tgif/), an interactive 2-D drawing tool under X11.
Gnuplot offers a variety of commands to set line and point properties,
including color, thickness, point shape, etc. The command test will
display a test page for the currently selected terminal type showing
the available pre-defined combinations of color, size, shape, etc.
The set style command can be used to define additional combinations.
GIF support is provided by an external library, libgd (http://www.libgd.org). Old versions of gd (versions 1.2 to 1.4) produce only GIF output. Versions 1.6 to 2.0.27 did not support GIF output because of patent concerns. However versions 1.6 and newer support PNG outputs, and 1.7 and newer support JPEG outputs. Version 2.0.28 of the Boutell gd library restored GIF functionality, and 2.0.29 added support for GIF animation. If your installation of gnuplot is linked to the gd library, you will get support for whatever formats (GIF, PNG, JPEG) are in that version of gd.
In any case, it is easy to convert from one format to another. To convert a PNG
output into GIF, you can either use the command line (e.g.
convert f.png f.gif or nconvert -out gif f.png) or any GUI
program. Another possibility is to output the image as (encapsulated)
postscript and convert (export) it into GIF or PNG by ghostscript, e.g.
convert -density 150 f.eps f.gif or by any ghostscript-based GUI like
gsview, gv or kghostview.
First have a look at animate.dem in the demo directory of gnuplot. Basically, animated graphs are a sequence of plots in a suitable format.
If your installation of gnuplot is linked with gd 2.0.29 or newer (see previous entry), the gif terminal can generate directly an animated GIF.
Otherwise, have a look at the tool whirlgif 3.04, available at http://www.danbbs.dk/ dino/whirlgif. It reads run-length encoded GIF files and packs them into a minimal animation. On the web-pages you will find a manual and an example.
You can also write a small script to get gnuplot to output a family of GIF files, then have it execute some animator such as gifsicle: http://www.lcdf.org/ eddietwo/gifsicle or gifmerge http://the-labs.com/GIFMerge.
mpeg_encode will encode a sequence of images into an mpeg format movie.
Implicit graphs or curves cannot be plotted directly in gnuplot. However there is a workaround.
gnuplot> # An example. Place your definition in the following line: gnuplot> f(x,y) = y - x**2 / tan(y) gnuplot> set contour base gnuplot> set cntrparam levels discrete 0.0 gnuplot> unset surface gnuplot> set table 'curve.dat' gnuplot> splot f(x,y) gnuplot> unset table gnuplot> plot 'curve.dat' w lThe trick is to draw the single contour line z=0 of the surface z=f(x,y), and store the resulting contour curve to a gnuplot datafile.
A plot with filled area between two given curves requires a parametric plot with
filledcurves closed.
The example below demonstrates this for two curves f(x) and g(x) with a tricky
"folded" parameter t:
set parametric f(x)=cos(x) g(x)=sin(x) xmax=pi/4 set xrange [0:xmax] set trange [0:2*xmax] path(t) = ( t<= xmax ? f(t) : g(2*xmax-t) ) fold(t) = (t <=xmax ? t : 2*xmax - t) plot fold(t),path(t) with filledcurves closed
Note that the above code fills area between the two curves, not area satisfying
inequality g(x)<f(x). If you want the latter, you should use the ternary
operator in path(t) to return an undefined value (0/0) if the inequality
is not satisfied.
See the documentation for help parametric, help filledcurves, and
help ternary.
You do set pm3d; splot 'a.dat' and no plot but colorbox appears.
Obviously, there is no blank line in between two subsequent scans (isolines) in
the data file. Add blank lines! If you are curious what this means, then don't
hesitate to look to files like demo/glass.dat or demo/triangle.dat
in the gnuplot demo directory.
You can find useful the following awk script (call it e.g. addblanks.awk)
which adds blank lines to a data file whenever number in the first column
changes:
/^[[:blank:]]*#/ {next} # ignore comments (lines starting with #)
NF < 3 {next} # ignore lines which don't have at least 3 columns
$1 != prev {printf "\n"; prev=$1} # print blank line
{print} # print the line
Then, either preprocess your data file by command
awk -f addblanks.awk <a.dat or plot the datafile under a unixish platform
by gnuplot> splot "<awk -f addblanks.awk a.dat".
Use set view map; unset surface or set pm3d map rather than set view 180,0. The latter facilitates drawing matrices or data files as maps, even without the necessity for matrix-like data organization (gridding). It is possible to decrease the output postscript file size by postprocessing it by pm3dCompress.awk or pm3dConvertToImage.awk.
Note there is a new plotting style with image for plotting 2D color
images with support for almost arbitrary text or binary files in "Patches"
section on gnuplot's sourceforge site
http://www.sourceforge.net/projects/gnuplot/.
Use the explicit (see also implicit) switch of the pm3d style:
gnuplot> set pm3d explicit gnuplot> splot x with pm3d, x*y with points
Well, it is very simple even though it is hard to discover: unset clabel.
set contour both; set cntr levels 100 unset clabel unset surface splot x*y with line lt -1 pause -1 splot x*y with line palette
Another solution requires to write contours into a temporary file using the table terminal:
set contour base; set cntrparam levels 15; unset surface; set view map splot x*x+y*y; pause -1 set table 'contour.dat' replot unset tableNow, for drawing it in 2D, do
reset plot 'contour.dat' with line -1and for contours in 3D do
reset
# Change single blank lines to double blank lines
!awk "NF<2{printf\"\n\"}{print}" <contour.dat >contour1.dat
splot 'contour1.dat' with line -1
See also the following question "How to overlay contour plot over pm3d map/surface".
Labelling contours by their z-value can be achieved by a suitable script
generating automatically the appropriate set label commands; you can find
one at gnuplot scripts page
http://gnuplot.sourceforge.net/scripts/index.html#tricks-here.
This requires you to write contours into a temporary file using the table
terminal, and then use this file in the final drawing without set contours.
The following example demonstrates this for a map; for surface, remove
set pm3d map and put set ticslevel 0.
# Write contours of function x*x-y*y to a (temporary) file
set contour base; set cntrparam level 20
unset surface
set table 'contour.dat'
splot x*x-y*y
unset table
# Change single blank lines to double blank lines
!awk "NF<2{printf\"\n\"}{print}" <contour.dat >contour1.dat
# Draw the plot
reset
set palette gray
set palette gamma 2.5
set pm3d map
set pm3d explicit
splot x*x+y*y with pm3d, 'contour1.dat' with line lt -1
!rm contour.dat contour1.dat
The last command deletes the two temporary files.
It is possible to draw colors facets of a 3D objects, organized in such a file:
# triangle 1 x0 y0 z0 <c0> x1 y1 z1 <c1> x2 y2 z2 <c2> x2 y2 z2 <c2> # triangle 2 x y z ...
Notice the positioning single and double blank line. <c> is an optional color.
Then plot it by (either of splot's):
set pm3d set style data pm3d splot 'facets.dat' splot 'facets_with_color.dat' using 1:2:3:4
Note that you avoid surface lines by set style data pm3d or splot ... with pm3d.
In the above example, pm3d displays triangles as independent surfaces. They are plotted one surface after another, as found in the data file. Parts overlapping in 2D projection are overdrawn.
Gnuplot is not 3D modeling program. Its hidden routines apply for points and lines, but not for faces. Without handling the data as a collection of faces, there would be no surface anything could be hidden behind. The 'hidden3d' algorithm works by using the input data in two ways: first, to set up a collection of triangles (made from a mesh of quadrangles) that form the surface, second as a collection of edges. It then goes through all those edges, checking what parts of them are not hidden behind any faces, and draws those.
Consequently, gnuplot won't draw your surface or 3D object as a virtual reality. It works OK for set pm3d map but for true 3D you would be probably more happy writing a convertor of your facets into a VRML file.
I think it is this one, for example: set palette rgbformulae -25,-24,-32. Can somebody prove this?
Too many things to be named here. Please refer to the NEWS file in the source distribution, or the "New features" section in the gnuplot documentation.
To see a list of the available graphic drivers for your installation of
gnuplot, type set term.
Some graphics drivers are included in the normal distribution,
but are uncommented by default. If you want to use them, you'll
have to change file gnuplot/src/term.h, and recompile.
Yes.
Various clustered and stacked histogram styles are supported in gnuplot version 4.2 as separate style types.
In older gnuplot versions you can use the style with boxes for bar charts.
To get filled boxes, use set style fill.
Bernhard Reiter wrote an AWK script to post-process fig-terminal output.
This may be useful with older versions of gnuplot. Please have a look at
http://www.usf.uni-osnabrueck.de/ breiter/tools/gnuplot/barchart.en.html.
It's not possible in gnuplot, but have a look at http://www.usf.uni-osnabrueck.de/ breiter/tools/piechart/piecharts.en.html
It's not possible in gnuplot, but have a look at
http://ricardo.ecn.wfu.edu/ cottrell/qplot. The corresponding
file qplot.zip can be obtained from the contrib directory
on any gnuplot server.
Yes. set multiplot.
If you use the postscript terminal and plot one graph per page you can use the program mpage (http://www.mesa.nl/pub/mpage) to print multiple logical pages per physical page. A similar program is the psnup program in the psutils package. This package is available at any CTAN mirror.
Yes. You can have 2 x- and 2 y-axes per plot. The additional axes are called
x2 and y2. See help plot.
This is possible by the new plot "-" possibility. The
plot "-" command allows to read the data to be plot from
standard input or the current batch job.
gnuplot> plot "-" 1 1 2 4 3 9 e
The enhanced option in some terminals (currently postscript, Presentation Manager, png, pdf, and x11) lets you use sub- and superscripts. It also allows to use Greek letters and symbols via symbol fonts, to the extent that these are supported by the underlying font libraries on your system. Versions through 2.0.15 of libgd (needed for png and jpeg) must be patched in order to handle symbol fonts.
You might try using the LATEX terminal type and putting text
like "\\alpha_{3}" or '\alpha_{3}' .
If you include your gnuplot-graphs into a LATEX document
you can use the LATEX-package psfrag to typeset any characters
into your graphs.
One more possibility is to use the MetaPost terminal. It supports TEX syntax and is converted onto encapsulated PostScript by mpost.
To obtain accented characters like ü or n in your labels you should use 8bit character codes together with the appropriate encoding option. See the following example:
gnuplot> set encoding iso_8859_1 gnuplot> set title "M\374nchner Bierverbrauch \374ber die Jahre" gnuplot> plot "bier.dat" u 1:2
Consequently, you can type labels in Czech, French, Hungarian, Russian... by means of an appropriate set encoding. However, you cannot mix two encodings in one file (e.g. accents for west and east latin encodings).
A more general solution is to use UTF-8 encoded fonts, and type the UTF-8 characters directly into gnuplot. This works for many terminal types but not, unfortunately, PostScript.
Use set size square.
Some terminals can, others can't. Some allow you to choose a font size for the entire plot. Terminals supporting the "enhanced text" mode (like postscript, pm, x11, png, pdf) allow you to change fonts and text sizes within a plot. Look at the help for these terminals.
By specifying ? as a data value, as in
1 2
2 3
3 ?
4 5
See also set missing. See also set datafile commentschars for specifying comment characters in data files.
This can be specified with various options for the command plot,
for example plot 'a.dat' every 2.
Depending on context, the main methods are:
set arrow .... .... nohead where you have to compute
explicitly the start and the end of the arrow.
Easily: by a command plot 'a.dat'. In 3D, use splot 'a.dat' - but don't forget to put a blank line in between two subsequent scans (isolines), otherwise you will get an error that the data is not gridded; see also question 3.10. If your data are not gridded, then use set dgrid3d {many options}.
You cannot directly: gnuplot supports replot command, not
remultiplot. You have to write the complete sequence of commands since
set multiplot till unset multiplot into a script file. Then
you can load the script into gnuplot as many times as you need for
replotting the drawing to different terminals or output files.
First, try to see whether it actually is a bug, or whether it is a feature which may be turned off by some obscure set-command.
Next, see whether you have an old version of gnuplot; if you do, chances are the bug has been fixed in a newer release.
Fixes for bugs reported since the release of the current version are held in the patches directory at gnuplot distribution sites. Before submitting a bug report, please check whether the bug in question has already been fixed.
If, after checking these things, you still are convinced that there is a bug, proceed as follows. If you have a fairly general sort of bug report, posting to ~comp.graphics.apps.gnuplot is probably the way to go. If you have investigated a problem in detail, especially if you have a context or unified diff that fixes the problem, please e-email a report to gnuplot-bug@lists.sourceforge.net.
The bug-gnuplot list is for reporting and collecting bug fixes, the
~comp.graphics.apps.gnuplot
newsgroup will be more help for
finding work arounds or actually solving gnuplot related problems. If
you do send in a bug report, be sure and include the version of gnuplot
(including patchlevel) as shown by the command show version long,
terminal driver, operating system, an exact description of the bug and
input which can reproduce the bug. Failure to indicate these details can
render a solution to your problem almost impossible. Also, any context
diffs should be referenced against the latest official version of
gnuplot if at all possible.
On systems supporting pipes, you can pipe commands to gnuplot from other programs. Many applications with gnuplot as the graphics engine, like Octave (http://www.octave.org), uses this method. This also works from a cgi script to drive gnuplot from a forms-based web page.
John Campbell (jdc@nauvax.ucc.nau.edu) modified a much earlier version of gnuplot (3.5) to be a library of C subroutines callable from a C program. Gnuplot itself has changed radically since then, and we are not aware of any plans to create a similar library based on the current version.
Many extensions or patches are available on the "Patches" page of the gnuplot development site http://sourceforge.net/tracker/?group_id=2055&atid=302055. The current development version will generally include some of these being debugged for inclusion in a later official release of gnuplot.
Older extensions, which may or may not work with the current version, are available from ftp.ucc.ie in /pub/gnuplot/contrib/.
Some extensions available:
Gnuplot has been and is a plotting program, not a data processing or mathematical program suite. Therefore gnuplot can't do that. Look into the demo file "bivariat.dem" for a basic implementation of an integration.
For more sophisticated data-processing read the next section.
gnuplot alone is not suited very well for this. One thing you might try
is fudgit, an interactive multi-purpose fitting program written by
Martin-D. Lacasse (isaac@frodo.physics.mcgill.ca). It can use
gnuplot as its graphics back end and is available from
ftp.physics.mcgill.ca in /pub/Fudgit/fudgit_2.33.tar.Z
and from
the main Linux server, tsx-11.mit.edu and its numerous mirrors around
the world as /pub/linux/sources/usr.bin/fudgit-2.33.tar.z.
Versions are available for AIX, Data General, HP-UX, IRIX 4, Linux,
NeXT, Sun3, Sun4, Ultrix, OS/2 and MS-DOS. The MS-DOS version is
available on simtel20 mirrors (simtel20 itself has closed down) in the
"math" subdirectory as fudg_231.zip.
Carsten Grammes has written a fitting program which has been merged into gnuplot 3.7.
Michael Courtney has written a program called lsqrft, which uses the Levenberg-Marquardt - algorithm for fitting data to a function. It is available from hobbes.nmsu.edu in /pub/os2/apps/analysis/lsqrft15.zip; sources, which should compile on Unix, and executables for MS-DOS and OS/2 are available. There is an interface to the OS/2 presentation manager.
You might also want to look at the applications developed by the Software Tools Group (STG) at the National Center for Supercomputing Applications. Ftp to ftp.ncsa.uiuc.edu and get the file README.BROCHURE for more information.
You can also try pgperl, an integration of the PGPLOT plotting package with Perl 5. Information can be found at http://www.ast.cam.ac.uk/AAO/local/www/kgb/pgperl, the source is available from ftp.ast.cam.ac.uk in /pub/kgb/pgperl/ or linux.nrao.edu in /pub/packages/pgperl/.
Another possibility is Octave. To quote from its README: Octave is a high-level language, primarily intended for numerical computations. Octave is licensed under GPL, and in principle, it is a free Matlab clone. It provides a convenient command line interface for solving linear and nonlinear problems numerically. The latest released version of Octave is always available from http://www.octave.org. By the way, octave uses gnuplot as its plotting engine, so you get a data-processing program on top of gnuplot.
Finally, there is scilab at http://www-rocq.inria.fr/scilab/ doing about the same as matlab. It is free but copyrighted software.
If your mouse is not working, try to hit 'm' in the interactive terminal to switch mousing on/off. See below for the list of supported interactive terminals.
If it still does not run, then either gnuplot has not been configured or compiled with mouse support, or you have not properly installed it, or running an older version of gnuplot (check your PATH).
If your gnuplot is running as the plotting engine of Octave under X11, then please put set mouse into your $HOME/.gnuplot (preferred than putting gset mouse into $HOME/.octaverc). This is needed only for gnuplot 4.0: according to its help x11_mouse, gnuplot 4.0 under x11 running through a pipe needs set mouse to be executed before launching the x11 plot window.
There are several hotkeys available in interactive terminals. Currently the following interactive terminals support hotkeys and mousing: OS/2 Presentation Manager, X11, Windows, WX, and GGI. Hit 'h' in the terminal to get list of hotkeys. See help new-features or the Features introduced in version 4.0 section in the docs for a brief guide over mousing and hotkeys. Further, you may read help mouse and help bind for more information.
If your patch is small, mail it to gnuplot-beta@lists.sourceforge.net, with a thorough description of what the patch is supposed to do, which version of gnuplot it is relative to, etc. Well, please do it always with respect to the current development version of gnuplot (see 'cvs' above).
Nowadays, the preferred way of submitting, commenting and upgrading patches are via 'Patches' section on http://www.sourceforge.net/projects/gnuplot/. You may want to send a note to gnuplot-beta@lists.sourceforge.net for more lively discussion.
Join the gnuplot beta test mailing list by sending a mail
containing the line
subscribe gnuplot-beta
in the body (not the subject) of the mail to
Majordomo@lists.sourceforge.net.
Also check with http://sourceforge.net/projects/gnuplot about latest source for beta releases for development.
Please submit your questions (along with the answer) to gnuplot-beta@lists.sourceforge.net.
Use a parametric plot. An example:
gnuplot> set parametric gnuplot> a=1 gnuplot> b=3 gnuplot> c=2 gnuplot> d=4 gnuplot> x1(t) = a+(b-a)*t gnuplot> x2(t) = c+(d-c)*t gnuplot> f1(x) = sin(x) gnuplot> f2(x) = x**2/8 gnuplot> plot [t=0:1] x1(t),f1(x1(t)) title "f1", x2(t), f2(x2(t)) title "f2"
You can also use gnuplot's ability to ignore mathematically undefined
expressions: the expression 1/0 is silently ignored, thus a
construction like
gnuplot> set xran [-10:10] gnuplot> plot (abs(x)>0.5?1/0: x**2)plots a quadratic function only for
|x| < 0.5.
If your system supports the popen() function, as Unix does, you should be able to run the output through another process, for example a short awk program, such as
gnuplot> plot "< awk ' { print $1, $3/$2 } ' file.in"
The plot command is very powerful and is able to do some
arithmetic on datafiles. See help plot.
The above filtering works seamlessly under Unixes and OS/2. It can work under MS
Windows as well, but that is for experienced users: (A) When gnuplot has been
compiled by cygwin with the unixish way of ./configure; make with
X11 terminal instead of the 'windows' terminal. You have to run this under an
X-server. This procedure is out of knowledge for usual users, but powerful
for others. (B) Compile gnuplot yourself by makefile.mgw or
makefile.cyg and set PIPES=1 therein. The drawback is that
each wgnuplot.exe will be accompanied by a boring shell box.
There is a set of LATEX macros and shell scripts that are meant to make your life easier when using gnuplot with LATEX. This package can be found on ftp.dartmouth.edu in pub/gnuplot/latex.shar, by David Kotz. For example, the program "plotskel" can turn a gnuplot-output file plot.tex into a skeleton file skel.tex, that has the same size as the original plot but contains no graph. With the right macros, the skeleton can be used for preliminary LATEX passes, reserving the full graph for later passes, saving tremendous amounts of time.
Use the save and load commands for this; see help save
and help load for details.
You can save the current terminal and restore it later without touching the filesystem by set term push and set term pop, respectively.
If the data in a data file for splot is arranged in such a way that each one has the same number of data points (using blank lines as delimiters, as usual), splot will plot the data with a grid. If you want to plot just lines, use a different number of data entries (you can do this by doubling the last data point, for example). Don't forget to set parametric mode, of course.
An example:
gnuplot> f(x,y) = x**2 + y **2 gnuplot> x(u) = 3*u gnuplot> yu(x) = x**2 gnuplot> yl(x) = -x**2 gnuplot> set parametric gnuplot> set cont gnuplot> splot [0:1] [0:1] u,yl(x(u))+(yu(x(u)) - yl(x(u)))*v,\ > f(x(u), (yu(x(u)) - yl(x(u)))*v)
Most gnuplot features are controlled by a corresponding set/unset command.
If a feature is enabled by default, or by using set <feature>, then you
should be able to turn it by using set no<feature>. However, the prefered
syntax since version 4.0 is unset <feature>.
On unix-like systems, commands to gnuplot can be piped via stdin.
Output from gnuplot's print command can be read via a named pipe.
On M$ Windows platforms, due to the lacking standard
input (stdin) in GUI programs, you need to use the helper program pgnuplot
which should be included in your gnuplot for M$W distribution package.
Reading gnuplot output may be impossible.
The most straightforward way is to use a UTF-8 font, and type in the
character (Unicode code point #x210F) directly.
This does not work in PostScript, however, so you must use approximations
like
@{/=56 -} {/=24 h} or
{/=8 @{/Symbol=24 -} _{/=14 h}}
In the latter, the "-" (a long one in /Symbol) is non-spacing and 24-pt.
The 14-pt "h" is offset by an 8-pt space (which is the space preceding
the "_") but smaller, since it's written as a subscript.
But these don't look too much like the hbar we're used to, since the bar
is horizontal instead of sloped. I don't see a way to get that. I
tried using an accent (character 264 in iso-latin-1 encoding), but I haven't found a
way to scale and position the pieces correctly.
One more possibility would be {/=14 @^{/Symbol=10 -}{/=14 h}}.
The reduced Planck's constant can be set very easily by using the
AMS-LaTeX PostScript fonts which are available from
http://www.ams.org/tex/amsfonts.html
(also included in many LaTeX
distributions). Gnuplot (confer the help about fontpath) and the
PostScript interpreter (usually Ghostscript) have to know where the
file msbm10.pfb (or msbm10.pfa) resides. Use
{/MSBM10 \175} to produce \hslash which is a "h"
superimposed by a sloped bar. The standard \hbar (horizontal
bar) has the octal code 176. Please note that h-bar exists only as an
italic type.
As with Planck's constant, the most straightforward way is to use a
UTF-8 font, and type in the 
character (Unicode code point #x2299) directly.
Well, you probably don't want a blank page, but page with a just a title (overprinting title in another graph in multiplot page):
reset; unset xtics; unset ytics unset border; unset key set title 'Title on an empty page' plot [][0:1] 2
Gnuplot does not do font handling by itself; it must necessarily leave that to the individual device support libraries. Unfortunately, this means that different terminal types need different help in finding fonts. Here are some quick hints. For more detailed information please see the gnuplot documentation for the specific terminal type you are having problems with.
setenv GNUPLOT_DEFAULT_GDFONT verdana
set term x11 font "mbfont:sazanami mincho,vera,20"
$ gnuplot_x11 :== $disk:[directory]gnuplot_x11
$ gnuplot :== $disk:[directory]gnuplot.exe
$ def/job GNUPLOT$HELP disk:[directory]gnuplot.hlb
Then run gnuplot from your command line, and use
set term x11.
If you run gnuplot on Unix systems, be sure that the newest
gnuplot_x11 is the first in your search path.
Command which gnuplot_x11 will help you.
Gnuplot treats all numbers less than 1e-08 as zero, by default. Thus, if you are trying to plot a collection of very small numbers, they may be plotted as zero. Worse, if you're plotting on a log scale, they will be off scale. Or, if the whole set of numbers is "zero", your range may be considered empty:
gnuplot> plot 'test1'
Warning: empty y range [4.047e-19:3e-11], adjusting to [-1:1]
gnuplot> set yrange [4e-19:3e-11]
gnuplot> plot 'test1'
^
y range is less than `zero`
The solution is to change gnuplot's idea of "zero":
gnuplot> set zero 1e-20
For more information, type help set zero.
Obviously, it draws (unless there is an error in the script file), but the plot dissappears immediately when the script is completed.
Solution 1: Put a pause -1 after the plot command in the file, or at the
file end.
Solution 2: Use command gnuplot filename.gp - (yes, dash is the last
parameter) to stay in the interactive regime when the script completes.
Solution 3A: On an X-Window System system, you can also use the -persist
option, the X11 window is then not closed. Close the X11 window by typing "q"
when the focus is on it.
Solution 3B: On M$ Windows, you can also use either -persist or
/noend.
Solution 4: For OS/2 PM terminal, use set term pm persist or
set term pm server. For X11 terminal, use set term x11 persist.
Gnuplot does integer, and not floating point, arithmetic on integer expressions. For example, the expression 1/3 evaluates to zero. If you want floating point expressions, supply trailing dots for your floating point numbers. Example:
gnuplot> print 1/3
0
gnuplot> print 1./3.
0.333333
This way of evaluating integer expressions is shared by both C and Fortran.
You may need to flush the output with a closing set output.
The LATEX2
-core no longer includes the commands
"
Diamond" and "Box"; they are included in the latexsym package.
Other symbols are taken from the asmsymb package.
Both of these are part of the base distribution and thus part of any LaTeX
implementation. Please remember to include these packages in your LaTeX document.
The examples have been removed from the NASA site mentioned in older documentation. You can find the version 4.0 examples at http://gnuplot.sourceforge.net/demo. Version 4.2 examples are at http://gnuplot.sourceforge.net/demo_4.2.
You can call gnuplot by using a short Perl-script like the following:
#!/usr/local/bin/perl -w open (GP, "|/usr/local/bin/gnuplot -persist") or die "no gnuplot"; # force buffer to flush after each write use FileHandle; GP->autoflush(1); print GP,"set term x11;plot '/tmp/data.dat' with lines\n"; close GP
Gnuplot closes its plot window on exit. The close GP
command is executed, and the plot window is closed even before you have
a chance to look at it.
There are three solutions to this: first, use the pause -1
command in gnuplot before closing the pipe. Second, close the pipe
only if you are sure that you don't need gnuplot and its plot window
anymore. Last, you can use the command line option -persist: this
option leaves the X-Window System plot window open.
Gnuplot 3.7's main contributors are (in alphabetical order) Hans-Bernhard Broeker, John Campbell, Robert Cunningham, David Denholm, Gershon Elber, Roger Fearick, Carsten Grammes, Lucas Hart, Lars Hecking, Thomas Koenig, David Kotz, Ed Kubaitis, Russell Lang, Alexander Lehmann, Alexander Mai, Carsten Steger, Tom Tkacik, Jos Van der Woude, James R. Van Zandt, and Alex Woo. Additional substantial contributors to version 4.0 include Ethan Merritt, Petr Mikulík and Johannes Zellner.
This list was initially compiled by John Fletcher with contributions from Russell Lang, John Campbell, David Kotz, Rob Cunningham, Daniel Lewart and Alex Woo. Reworked by Thomas Koenig from a draft by Alex Woo, with corrections and additions from Alex Woo, John Campbell, Russell Lang, David Kotz and many corrections from Daniel Lewart. Again reworked for gnuplot 3.7 by Alexander Mai and Juergen v.Hagen with corrections by Lars Hecking, Hans-Bernhard Broecker and other people. Revised for gnuplot 4.0 release by Petr Mikulík and Ethan Merritt. Revised for gnuplot 4.2 release by Petr Mikulík and Ethan Merritt.