Project gnuplot

‘ GNUPLOT & ITS APPLICATIONS’
Sabyasachi Ray
Roll no.03 , Part 2
Department of physics
University of North Bengal

 Scientists runs simulations or take
measurements. These data need to be
presented in an appealing and professional
manner.
 Sometimes there are a lot of data. Sometimes
it is difficult to make the interesting features
come out right. Sometimes many plots must
be produced.
 Manually doing plot with indefinitely large no.
of data are very difficult job. These
different necessity of plotting insists people
to develop some way to save time as well
as hard working.

GNUPLOT: a SOLUTION
 There are lots of other plotting tools available
for creating 1D or 2D plots from numerical
data in different operating systems
 Though many plotting tools are available now-
a-days , one of the best advantages of ‘gnuplot’
over (say) MATHEMATICA or MAPLE GRAPHS is
that it is incredibly easy to write scripts to
automatically create graphs for people from
raw data.

What is gnuplot?
 gnuplot is a command-driven interactive function
and data plotting program. It can be used to plot
functions and data points in both two and three
dimensional plots in many different formats.

GNUPLOT : HISTORY
 Software developer:
Original software:
THOMAS WILLIAMS,COLIN KELLEY
gnuplot 2.0 additions:
RUSSELL LANG, DAVID KOTZ, JOHN CAMPBELL
GERSHON ELBER,ALEXANDER WOO & MANY
OTHERS
HANS-BERNHARD BRӦKER, ETHANA-MERIT AND
OTHERS

GNUPLOT: supporting
operating system
 precompiled executables and source code for
gnuplot is downloadable for
1) windows ,
2) DOS,
3) Unix,
4) Linux.
Gnuplot is preinstalled in most of the LINUX
system

LINUX
 ‘gnuplot’ is a software works in almost every
platform. I do my PROJECT WORK in
FEDORACORE 3 (LINUX) platform. As scientific
world mostly uses the LINUX platform.

WORLD-WIDE LINUX
 The governments of many third world nations
like BRAZIL, SPAIN,CHINA,PERU,PAKISTAN and
INDIA are actively involved in promoting
LINUX and associate open source softwares.
 LINUX has found its way to Cell-Phones,
desktops and office computers.
 the LHC itself is controlled by LINUX

Installing Fedora:requirement
 A pentium-class PC (at least 200 MHz for text mode;
400 MHz Pentium II for GUI)
 64 Mb RAM (for text mode)
 192 Mb RAM (for GUI mode)

Minimum hard-disk space
620Mb for minimum custom install
2.3 Gb for personal desktop
3.0 Gb for workstation
1.1 Gb for server install
A everything install requires at least
6.9Gb

Linux: installation
 I installed fedora core 3 in a desktop.
 There are different steps one should follow while
installing.
 The important thing is the PARTITION of hard drive.

Linux: installation
 I choose …
 DISK PARTITION
 MANUALLY⤶
 /boot=100 Mb
 /swap=996 Mb
 /home=10001 Mb
 / =10001 Mb
 free==1961 Kb

Plotting:What does gnuplot offer?
 Plotting two-dimensional functions and data points in
many different styles (points, lines, error bars)
 Plotting three-dimensional data points and surfaces in
many different styles (contour plot)
 Algebraic computation in integer, float and complex
arithmetic
 User-defined functions
 Support for a large number of operating systems, graphics
file formats and output devices
 Extensive on-line help
 TEX-like text formatting for labels, titles, axes, data
points
 Interactive command line editing and history .

Starting : GNUPLOT
 To start gnuplot in LINUX we have to simply type
gnuplot in the command line of the linux terminal as
follows:
 gnuplot
 This command gives:

Starting : GNUPLOT
G N U P L O T
Version 4.0 patchlevel 0
last modified Thu Apr 15 14:44:22 CEST 2004
System: Linux 2.4.23
Copyright (C) 1986 - 1993, 1998, 2004
Thomas Williams, Colin Kelley and many others
This is gnuplot version 4.0. Please refer to the documentation
for command syntax changes. The old syntax will be accepted
throughout the 4.0 series, but all save files use the new syntax.
Type `help` to access the on-line reference manual.
The gnuplot FAQ is available from
http://www.gnuplot.info/faq/
Send comments and requests for help to
<gnuplot-info@lists.sourceforge.net>
Send bugs, suggestions and mods to
<gnuplot-bugs@lists.sourceforge.net>
Terminal type set to 'x11'
gnuplot>

Starting : GNUPLOT
Now gnuplot is ready to
perform different commands
that it supports

Gnuplot: functions
 abs(x) absolute value of x, |x|
 acos(x) arc-cosine of x
 asin(x) arc-sine of x
 atan(x) arc-tangent of x
 cos(x) cosine of x, x is in radians.
 cosh(x) hyperbolic cosine of x, x is in radians
 erf(x) error function of x
 exp(x) exponential function of x, base e
 inverf(x) inverse error function of x
 invnorm(x) inverse normal distribution of x

Gnuplot: functions
 log(x) log of x, base e
 log10(x) log of x, base 10
 norm(x) normal Gaussian distribution function
 rand(x) pseudo-random number generator
 sgn(x) 1 if x > 0, -1 if x < 0, 0 if x=0
 sin(x) sine of x, x is in radians
 sinh(x) hyperbolic sine of x, x is in radians
 sqrt(x) the square root of x
 tan(x) tangent of x, x is in radians
 tanh(x) hyperbolic tangent of x, x is in radians
 E.T.C.

Gnuplot: as calculator
 gnuplot> print abs({3,4})
 5.0
 gnuplot> print log(100)
 4.60517
 gnuplot> print log10(100)
 2.0
 gnuplot> print rand(100)
 0.13348

 gnuplot> print sqrt(100)
 10.0
 gnuplot> print gamma(4)
 6.0
 gnuplot> print 3!
 6.0
 Like that

gnuplot> print 1/3
0
 How strange!!!

Gnuplot does integer,
and not floating point,
arithmetic on integer
expressions
gnuplot> print 1./3.
0.333333

gnuplot: plotting applications
 the primary commands in Gnuplot:-
 plot -2D
 splot -3D
 replot.

Gnuplot: plotting functions
 To plot functions simply one have to type: plot
[function] at the gnuplot> prompt.
 say plot sin(x) to draw a first figure.
 Say replot sin(x)**2 to add a second plot
 Say plot sin(x),-sin(x) to plot two graphs at once.
 Also one can define external function as
gnuplot> f(x)=3*x**4
gnuplot> plot f(x)

 gnuplot> plot sin(x)

gnuplot> replot sin(x)**2

gnuplot> f(x)=3*x**4
gnuplot> plot f(x)

 gnuplot> splot sin(x*y/20)

gnuplot: Plotting data
 For example my data file, force.dat , might look like:
 0.000 0 0
 0.001 104 51
 0.002 202 101
 0.003 298 148
 0.0031 290 149
 0.004 289 201
 0.0041 291 209
 0.005 310 250
 0.010 311 260
 0.020 280 240

gnuplot: Plotting data
 One can display plot data by typing:
 gnuplot> plot "force.dat" using 1:2 title 'Column',
"force.dat" using 1:3 title 'Beam’
 If the data are in multiple data files. In this case
one should plot by using a command like:
 gnuplot> plot "fileA.dat" using 1:2 title 'data A',
"fileB.dat" using 1:3 title 'data B'

gnuplot: plot command
customization
 Plots may be displayed in one of the styles: lines,
points, linespoints, impulses, dots, steps, fsteps,
histeps, errorbars, xerrorbars, yerrorbars,
xyerrorbars, boxes, boxerrorbars, boxxyerrorbars,
financebars, candlesticks or vector To specify the
line/point style use the plot command as follows:

 gnuplot> plot "force.dat" using 1:2 title 'Column'
with lines,
"force.dat" u 1:3 t 'Beam' w linespoints

gnuplot: PRINTING
 One can create a PostScript file of plot by using
the following :
 gnuplot> set terminal postscript
 gnuplot> set output "my-plot.ps"

gnuplot: Commands to Quit
 exit or quit command terminates gnuplot.
 Once one quit gnuplot, all of setting one made
will be lost.
 To save the current setting, use save command
followed by a file name in which parameters and
functions one defined are stored.
 gnuplot overwrites internal parameters in that
file without any warnings.

gnuplot: Commands to Save
Parameters
 gnuplot> save "savefile.plt"
 the saved file is a usual text file.
 one can edit the contents with a text editor.
 To draw a graph again with this file, we use the
load "savefile.plt" command at the gnuplot
command-line-
 gnuplot> load "savefile.plt"

application: gnuplot
 Now different kind of plotting and fitting that
I made are shown and explained in the next
coming slides.

simple ploting using sin(x)
 gnuplot> set output 'sin.pdf'

 To set the X range 0 to 5, [0:5]
 gnuplot> plot [0:5] sin(x)

 gnuplot> set angle degree
 gnuplot> set xrange[-270:270]

 gnuplot> set xrange [-2*pi:2*pi]
 gnuplot> a=0.5
 gnuplot> plot a*sin(x)

gnuplot: different styles available
 Now say some data file named "output.dat"
contains some nature as shown below.
 gnuplot> plot "output.dat" title ‘style1’ with lines.

gnuplot: different styles available
 gnuplot> plot "output.dat" title ‘style2’ with points

gnuplot: customizing styles
 gnuplot> plot "output.dat" title ‘style3’ with steps.

gnuplot: customizing styles
 gnuplot> plot "output.dat" title ‘style4’ with impulses

gnuplot: plotting of two sets of
data from a single data file
 The taken data file was named ‘ lateral density.txt’
 #lateral density.txt
 gnuplot> set output 'lateral density.pdf'
 gnuplot> set logscale

 gnuplot> set title 'PLOTTING OF TWO SETS OF
DATA FROM A DATA FILE‘
 gnuplot> set xrange [8:75]
 gnuplot> set yrange [0.1:3.0]
 gnuplot> set xlabel 'CORE DISTANCE(meter)'
 gnuplot> set ylabel 'DENSITY (particle/square meter)'
 gnuplot> plot 'lateral density.txt' u 1:3 title
'experimental density' w p 3,
 > 'lateral density.txt' u 1:2 title 'theoretical density' w p
4

 gnuplot> replot 'lateral density.txt' u 1:2 w l title
'theoretical graph‘

data from two different data
files and comparing them
 two data file are ‘absorptionrade’ & ‘absorptionsr’
Terminal type set to 'postscript'
Options are 'landscape noenhanced monochrome blacktext
dashed dashlength 1.0 linewidth 1.0 defaultplex
palfuncparam 2000,0.003
butt "Helvetica" 14'
 gnuplot> unset logscale
 gnuplot> set output 'absorption plot.ps'
 gnuplot> set xlabel 'Corrected thickness (mg/cm^2)'
 gnuplot> set ylabel 'counts/minute'
 gnuplot> set title'BETA ABSORPTION CURVE'

data from two different data
files and comparing them
 gnuplot> plot 'absorptionrade' w p 3,'absorptionsr'
title'comparing two sources'

gnuplot: linear curve fitting
 The data file that I choose for this case is:
 Age.txt
 gnuplot> set output 'age.ps'
 gnuplot> set title 'LINEAR CURVE FITTING FOR
DATA FILE USING GNUPLOT'
 gnuplot> set label 'z=zenith angle' at 1.1 ,1.6

 gnuplot> set xrange[1:1.5]
 gnuplot> set yrange[1.25:1.65]
 gnuplot> set xlabel 'sec(z)'
 gnuplot> set ylabel 'SHOWER AGE'
 gnuplot> f(x)=(m*x)+c
 gnuplot> m=1.4;c=-0.13
 gnuplot> fit f(x) 'age.txt' u 1:2 via m,c
 After 4 iterations the fit converged.and it is
shown on the screen

 gnuplot> set label 'f(x)=m*x+c,m=0.98,c=o.30' at 1.3,1.5
 gnuplot> plot 'age.txt' u 1:2:3 w yerrorbars title
'f(x)=m*x+c',
 > f(x) title 'fitted curve‘
these commands will produce :

linear curve fitting of more than
one plot in a single graph:
 My data file is ‘test.txt’ that I used in my this
particular plotting:
 gnuplot> set output 'manyplot.ps'
 gnuplot> set title ' PLOTING & LINEAR FITTING OF
MORE THAN ONE DATA SETS AT A TIME'
 gnuplot> set xlabel 'sec(z)'
 gnuplot> set ylabel 'shower age'
 gnuplot> set label 'z is the zenith angle' at 1.1,1.5
 gnuplot> set xrange[1:1.4]
 gnuplot> set yrange [1:1.55]

 gnuplot> f1(x)=a1*x+b1
 gnuplot> a1=-2;b1=3.28
 gnuplot> fit f1(x) 'test.txt' u 1:2 via a1,b1
 the fitting command for 2nd set of data points
are:
 gnuplot> a2=0.067;b2=1.173
 the fitting command for 3rd set of data points
are:
 gnuplot> a3=2;b3=-1.17

linear curve fitting of more than
one plot in a single graph:
 gnuplot> plot 'test.txt' u 1:2:3 w yerrorbars title' Fe',
 > f1(x) title 'y=0.31*x+0.95',
 > 'test.txt' u 1:4:5 w yerrorbars title ' Mixed',
 > f2(x) title 'y=0.17*x+1.07',
 > 'test.txt' u 1:6:7 w yerrorbars title ' proton',
 > f3(x) title 'y=.26*x+.83'
 These produce:

non-linear curve fitting
 For non-linear curve fitting I take the data file
'lateral density.txt'
 gnuplot> set output 'nonlinear.ps'
 gnuplot> set logscale
 gnuplot> set xrange [8:75]
 gnuplot> set yrange [0.1:3.0]
 gnuplot> set xlabel 'CORE DISTANCE(meter)'
 gnuplot> set ylabel 'DENSITY (particle/square meter)'
 gnuplot> set title 'NON-LINEAR FITTING (more than
one line)'
 gnuplot> set label 'y=(a+b*x+c*x**2+d*x**3)**3' at 30,1

 gnuplot> f1(x)=(a1+b1*x+c1*x**2+d1*x**3)**3
 gnuplot> a1=10;b1=20;c1=-4;d1=6;
 gnuplot> fit f1(x) 'lateral density.txt' u 1:2 via a1,b1,c1,d1
 gnuplot> f2(x)=(a2+b2*x+c2*x**2+d2*x**3)**3
 gnuplot> a2=1;b2=20;c2=-4;d2=6
 gnuplot> fit f2(x) 'lateral density.txt' u 1:3 via
a2,b2,c2,d2

 gnuplot> plot 'lateral density.txt' u 1:2 title 'theoretical' ,
 > f1(x) title 'a=1.77,b=-0.05,c=0.0011,d=-8.39e-6' ,
 > 'lateral density.txt' u 1:3 title 'experimental' ,
 > f2(x) title 'a=1.81,b=-0.06,c=0.001,d=-6.37e-6'

3-DIMENSIONAL PLOT USING
GNUPLOT:
 gnuplot> set output '3d.ps'
 gnuplot> set title 'the function choosen is sin(x*y/20)'
 gnuplot> set xr [-10:10]
 gnuplot> set yr [-10:10]
 gnuplot> set zr [-1:1]
 gnuplot> set xlabel 'x-axis'
 gnuplot> set ylabel 'y-axis'
 gnuplot> set zlabel 'z-axis'
 gnuplot> splot sin(x*y/20)

3-DIMENSIONAL PLOT USING
GNUPLOT:

The advantages
 The results are repeatable. This is very useful if one
needs many similar graphs, or if one potentially needs
to redo graphs with updated data.
 Plots can be produced automatically. Sometimes
plots take a long time, especially if there are much
data to be processed.
 Plots can be produced on a remote supercomputer,
written into a file, and then displayed locally. The data
do not need to be transferred.
 For a quick look at small datasets there are many
tools.
 For serious work gnuplot is one of the best.

Disadvantages
 Gnuplot has a limited set of line and point styles.
 Gnuplot cannot output symbolic equations or
formula and labels in most output formats.
 Gnuplot does a poor job of making contour plots.
 This is very hardworking job to remember all the
commands all time.

CONCLUSSION:
 In gnuplot there are many other integrated
facilities like animation. But due to shortage of
time I can not learn them.
 If I get an opportunity to use gnuplot in
future, this project will surely help me lot.
 More over I used this opportunity to learn little
bit about LINUX that would also help in advanced
studies.

Bibliography
 1> GNUPLOT 4.2 - A Brief Manual and Tutorial
Department of Civil and Environmental Engineering
Edmund T. Pratt School of Engineering
Duke University - Box 90287, Durham, NC 27708-0287
 2> www.gnuplot.info.
 3> G N U P L O T
 Version 4.0
 4> ‘fast track to LINUX, a beginners guide’ –digit February 2009.
 5> perfect Set up- Fedora Core 3 |HowtoForge-Linux Howtos and Tutorials
 www.howtoforge.com/perfect_setup_fedora_core_3
 6> book: BIBLE OF LINUX
 7> http://www.duke.edu/~hpgavin/gnuplot.html.
 8> http://www.cs.uni.edu/Help/gnuplot/
 9> Gnuplot Short Course- Tim Langlais

 10> http://t16web.lanl.gov/Kawano/gnuplot/index-e.html

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