Introduction to graphics/data plotting software

Setup for this tutorial:

If you are logged in under the username coult, please type the following commands in a shell window:

mkdir (your last name)
cd (your last name)
cp -R ../dat .
cp ../simple.tex .

If you are logged in on your own account, please type the following commands in a shell window:

cp -R ~coult/dat .
cp ~coult/simple.tex .

This document contains information on graphics capabilities of

Matlab
Mathematica
IDL
Other packages
LaTeX
Recommended reading

Matlab
What is it: Full-featured numerical linear algebra and data analysis package. Includes powerful, easy-to-use graphics features.
Note: The examples below are set up to be done in the order listed.
To start up matlab: In a shell window, type matlab.
To get help in matlab: Type help at the >> prompt. help (keyword) will display help for a keyword. To find all references to a word in the help files, type lookfor word, where word is the word you are looking for.
There is also on-line documentation for Matlab, found in various places. If you are in the newton lab, it is available locally. Otherwise, there is on-line documentation available here (fastest), here, and here, to name a few.

Examples:
- Simple 1-d plot of data
```
  >> load dat/x1
  >> plot(x1)
```
- Plotting a subset of the data
```
  >> plot(x1(1:64))
```
- Multiple plots in one window
```
  >> load dat/y1
  >> hold
  >> plot(y1,'red')
```
- Adding text to plots
```
  >> title('This is a nice plot.')
  >> xlabel('x')
  >> ylabel('y')
  >> gtext('Text can be placed with the mouse!')
```
- Multiple plots in multiple windows
```
  >> figure(2)
  >> plot(abs(x1-y1))
```
- Surface plots
```
  >> figure(1)
  >> hold
  >> load dat/x2
  >> surf(x2)
  >> figure(2)
  >> waterfall(x2)
```
- Exporting to a postscript file. Postscript is a graphics format (actually, it's a programming language) that can be printed by most printers or inserted into LaTeX documents, etc.
```
  >> print -deps figure.eps
```
  Note that this command does not actually print the figure, it just outputs it to a file called figure.eps. To print the figure, type in a shell (outside of matlab, but don't do this now)
```
lpr figure.eps
```
- Exporting to a PNG. PNG is a compressed image format. It doesn't print nicely the way postscript does, but you can display it on web pages. matlab tends to put a lot of white space around the figure when it outputs to a png, so you probably would want to use something like the program xv to crop it.
```
  >> print -dpng8 figure.png
```
- Other graphics capabilities: Mesh plots, data-and-error plots, etc. type 'help' at the matlab prompt for help.
Mathematica
What is it: Massive symbolic computation package, among other things. Also includes fully-customizable graphics features.
To start up mathematica, type
```
mathematica &
```
in a shell window.
To get help in Mathematica: Use the function browser, which you access by selecting the 'Open Function browser' menu item from the 'Help' menu. Or, if you know the name of a function and want to know more about it, type '?FunctionName'. FunctionName can be the full name of a mathematica function, or a string containing wildcards (*, ?), in which case mathematica will give you a list of function names which match that expression.
Examples:
- Plotting symbolic functions
```
sinplot=Plot[Sin[2*Pi*x],{x,0,1},PlotLabel->"This is a sine wave."]

sinplot3d=Plot3D[Sin[2*Pi*x]+Cos[8*Pi*y],{x,0,1},{y,0,1}]
```
- Parametric plots.
```
ParametricPlot[{Sin[t],Cos[t]},{t,0,2*Pi},
	AspectRatio->1,
	PlotRange->{{-2,2},{-2,2}}]
```
- Plotting 1-d data loaded from a file
```
x1=ReadList["dat/x1",Number];

ListPlot[x1,PlotJoined->True, AxesLabel->{"Indep. Variable","Dep. Variable"}]
```
- Example: Plotting 2-d data loaded from a file
```
x2=ReadList["dat/x2",Table[Number,{32}]];

ListPlot3D[x2]
```
- Combining multiple plots
```
cosplot=Plot[Cos[2*Pi*x,{x,0,1}];
Show[cosplot,sinplot];
```
- Note: Graphics options such as PlotLabel, AxesLabel, PlotRange, etc., work with all plotting functions. For a complete list of options of any function such as Plot, type Options[Plot]. For an explanation of an option, type e.g. ?PlotRange.
- Exporting to a postscript file. Select the cell with the left mouse button, and then switch to a text editor (such as emacs). In the text editor window, hit the middle mouse button. A bunch of garbage will appear. This is the postscript code for the graphics from mathematica. Now save the file as 'mma_figure.eps'.
- Other graphics capabilities: Animations, Multiple colors for 1-d plots, lighting and shading schemes for 2-d plots, density plots, contour plots, etc. Open function browser from the 'Help' menu and look under 'Graphics and Sound' for more information.
IDL
A feature-laden graphics and plotting package; see details.
Other packages
gnuplot, xyplot, maple, ... gnuplot and xyplot are simple plotting packages for data. They seem no better than matlab. Maple is, like Mathematica, a giant symbolic computation package; they have similar capabilities in terms of graphics, and Mathematica is better in many other ways.
Graphics in LaTeX
Source for a very simple latex document which uses the file "figure.eps": (This source can also be found in the file "simple.tex").
```
\documentstyle[epsf]{article}

\begin{document}

This is a simple graphic in \LaTeX:

\epsfxsize=400pt
\centerline{\epsffile{figure.eps}}

\end{document}
```
The [epsf] tells LaTeX to use the epsf package, which allows for importing of postscript-format files. \epsfxsize=400pt scales the graphic's width to 400 points; we could also specify the width in inches (in) or centimeters (cm). \centerline{ } centers the stuff between curly braces. \epsffile{figure.eps} is the command which loads the postscript file figure.eps and uses it as a graphic in the LaTeX document at the point where the command occurs. To compile the latex source and view the result, do this in a shell:
```
latex simple.tex
xdvi simple.dvi
```
Notice that the plot appears in color. If you print to a color printer, you'll get a nice hardcopy of your color plot! To print this, you need to change simple.dvi into a postscript file, which you do by running the following command in a shell:
```
dvips -o simple.ps simple.dvi
```
The file simple.ps may now be printed by using the lpr command, i.e. (don't do this now):
```
lpr simple.ps
```
Recommended reading
Here are some LaTeX books I like:
- A Guide to Latex2e, by Kopka and Daly, published by Addison-Wesley.
- LaTeX - User's Guide and Reference Manual, by Leslie Lamport.
- The LaTeX Companion, by Goossens, Mittelbach, and Samarin, published by Addison Wesley.
There are lots of other books too but those are the ones I use.
For Mathematica, there is:
- Mathematica, a System for Doing Mathematics by Computer, by Stephen Wolfram. The ultimate authority. Everything in this book, however, is also on the computer when you run the front end; use the Help Browser, found under the Help menu.

Setup for this tutorial:

Matlab

Examples:

Mathematica

IDL

Other packages

Graphics in LaTeX

Recommended reading