Linux Command: Screen

Screen is a terminal multiplexer that allows you to manage many processes through one physical terminal. Each process gets its own virtual window, and you can bounce between virtual windows interacting with each process. The processes managed by screen continue to run when their window is not active.

Screen offers the ability to detach from a session and then attach to it at a later time. When detached from a session, the processes screen is managing continue to run. You can then re-attach to the session at a later time, and your terminals are still there, the way you left them. It is handy because, with screen, you can launch your long program, leave it running on a lab computer, logout and go back home. Wa... Is it what you want in many cases?

How to use it? Run screen first on your terminal and then press "CTRL + A D" (CTRL A, CTRL D) to detach from the screen. Then you can do what ever you want, like logout and go home to have some fun. To attach back to the screen, just use "screen -r". For details, you might need to look at its manual.

LaTeX

Why LATEX?

The advantages of LaTeX are that

1. It's free.

2. It's available for many machines.

3. LaTeX files are ASCII and are portable. Because they're ASCII it's easy to discover how someone achieved an effect.

4. You can use the editor of your choice.

5. The typesetting's better, especially the maths.

6. Style changes are neater in LaTeX. Style files for many periodicals exist. Many Word users don't use styles or templates, and there's a limit to what can be done.

7. LaTeX is extensible. If you want a new feature, you can look around for a free add-on or write one yourself.

8. LaTeX's floats are no more awkward than Word's anchored frames, and the latter don't always work well.

Disadvantages are

1. Font selection is difficult compared to selection in Word and Framemaker.

2. LaTeX's not good at flowing text around pictures.

3. LaTeX encourages (almost insists on) structured writing and the separation of style from content. This is not the way that many people (especially non-programmers) are used to working.

4. Without a WYSIWYG front end, it's not always easy to find out how to do things.

For details, see Why LATEX?.


Short Introduction

There is a wonderful short introduction to LATEX by Wenguang Wang.

For more, see the official site www.latex-project.org

For Chinese version, see http://www.ctex.org


Math Symbols in LATEX

This is what I really interested in. There is a great introduction by on AMS site. This is a PDF file. A simpler web-based symbol list can be find at LaTex Math Symbols.

Leonhard Euler

Leonhard Euler (April 15, 1707 – September 18, 1783) was a Swiss mathematician and physicist. He is considered to be one of the greatest mathematicians who ever lived. Euler was the first to use the term "function" (defined by Leibniz in 1694) to describe an expression involving various arguments; i.e., y = F(x). He is credited with being one of the first after Isaac Newton to apply calculus to physics.

Born and educated in Basel, he was a mathematical child prodigy. He worked as a professor of mathematics in St. Petersburg, later in Berlin, and then returned to St. Petersburg. He is the most prolific mathematician of all time, his collected work filling 75 volumes. He dominated 18th century mathematics and deduced many consequences of the newly invented calculus. He was almost completely blind for the last seventeen years of his life, during which time he produced almost half of his total output.

The asteroid 2002 Euler is named in his honour.


This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Euler".

Some Tools I Want to Introduce

There are many tools we usually use in mathematical papers and projects. I want introduce some of them:

1. Xfig
2. LATEX
3. LyX
4. Matlab
5. Beamer
6. FEMLab

I am working on this.

Using LaTeX in Xfig

Introduction

xfig is a drawing package that's ideal for producing diagrams that can be imported into LATEX and many other word processing packages.

First familiarise yourself with the layout. Down the left is a panel of command buttons. Put the pointer on the icons to see what they do. The boxes along the bottom change according to the command you're using. Along the top is a menubar. The File option is concerned with loading and saving. The Help menu leads to full documentation.

Top left, under the menu bar, is a description of the current mode. Initially it says READY. Select a mode or load a file. Top right in the Mouse Buttons box, is a description of what the 3 mouse buttons currently do.

Unlike some graphics editors, xfig makes you select the function, then choose the object. Try drawing some objects. Keep an eye on the top corners of the window to get feedback. You'll notice that the objects sometimes have little boxes (handles) at their extremities. These are what you need to click on when you need to choose an object or vertex. Try moving and rotating some objects.

If you want to change the color of an object, fill it in, add arrows to lines, etc, click the edit button then select the object. A dialog box will appear that lets you change many features. If you want to change the same feature(s) of many objects, use the Update command.

For More: User's Manual

FAQ


Use LATEX In Your Fig

1. Inside xfig, add the LaTeX expressions to the figure, using $...$ to switch to math-mode where necessary.

2. Use the "special text" mode using the "Text flags" menu at the bottom of the screen to add math symbols.

3. Export the figure from xfig twice: firstly using the format "Combined PS/LaTeX (both parts)" to a file such as "test.pstex". This step will give two outputs: "test.pstex" and "test.pstex_t".

4. Create a driver file (e.g., test.tex) containing something like:

\documentclass{article}
\usepackage{epsfig}
\usepackage{color} (note: you might not might not need to do this)
\setlength{\textwidth}{100cm}
\setlength{\textheight}{100cm}
\begin{document}
\pagestyle{empty}
\input{test.pstex_t}
\end{document}

5. Run the commands:

latex fig1.tex
dvips -E test.dvi -o test.eps

6. You should now have a file named "test.eps" which can be included (with scaling and rotation if desired) in other LaTeX documents.



Installation

Download

For Unix/Linux users, see instruction . (It works fine for me with 3.2.4 amd 3.2.5 alpha. )

For Windows users, see instruction . (Never tried.)