TEX and LATEX

Someday you will want to publish the results of your research.  IGPP 
scientists typically use either Word of Latex for this purpose (some
old timers still use troff, a UNIX precursor to LaTeX).  Most of you
probably already know how to use Word.  It is very easy to use (WYSIWYG)
and is the "standard" word processor of choice in many institutions.  It
is not, however, ideal for writing scientific articles.  It has
particular difficulty handling equations and specialized typesetting
requirements.  A far better choice is TeX or LaTeX.  

Advantages of LaTeX:

(1) It is in the public domain so you are not supporting the Evil Empire.

(2) You can run it on Macs, PCs or UNIX machines.

(3) By using macros, it is a far more powerful and versatile system
  than all that pull down menu crap you find in most commercial 
  word processors.

(4) AGU uses LaTeX for its electronic submission of articles and abstracts.
  They provide macros to match the style of their journals so that preparing
  camera-ready copy is trivial.

(5) You can produce beautiful looking equations much more easily than with
  programs like Word. 

LaTeX takes a little while to learn at first, but you will find it well
worth your effort. 
 

************************* LaTeX on the Macs ******************************

On the Suns, you can invoke LaTeX just by typing latex and the file name.
This should also work on the Macs under X11 and is described below in the
notes.  However there exist LTteX interfaces for the Mac that make the
typesetting process much more convenient.  I have been using TeXShop, which
is free and should be installed on the Macs in the Barnyard.  There is
at least one other free version of LaTeX for the Macs but I don't have
any experience with it yet.  You can get TeXShop for your own machine
via fink but this is rather complicated--you might want to ask NetOps
for help in doing this.  I believe Tetex also has to be installed; Kris
Walker's Mac OSX web site has some details on this.

IMPORTANT:  When you first use TeXShop, go to Preferences/Engine and
set both "Path settings" to /sw/bin

With TeXShop you can just hit the typeset button and see the
typeset version side-by-side with your LaTeX source code.  The
program automatically generates a PDF file of your output.

**************************************************************************


A SIMPLE EXAMPLE

Use your favorite text editor to create the file samp1.tex:

                                                            (samp1.tex)
\documentclass{article}
\begin{document}
Today (\today) the rate of exchange between the British pound
and the American dollar is \pounds 1 = \$1.63, an increase of
1\% over yesterday.
\end{document}

This is an example that I got from my Latex book (Kopka and Daly,
A Guide to Latex2e)

The document must first define a document class.  Options are
book, report, article, or letter.  The guts of the document are
then enclosed between the \begin{document} and \end{document}
commands.

This example highlights some of the special characters and macros
in Latex.  The following characters are normally interpreted
as Latex commands:

$  &  %  #  _  {  }

To print these out in your text, you must precede them with
a backslash, i.e., 

\$  \&  \%  \#  \_  \{  \}

In this example, \today invokes a macro to print today's date
and \pound will print the British pound symbol.

From this example you can see that Latex is not WYSIWYG!  To
typeset this document, enter:

latex samp1

Assuming you have no errors in the input file, this will
generate the file samp1.dvi.  To preview this file, enter:

xdvi samp1

To convert the file to a Postscript file, enter:

dvips samp1 -o samp1.ps

Notice that Latex automatically indented the first line
of the paragraph.  To avoid this, use the \noindent
command for the target paragraph:

\documentclass{article}
\begin{document}
\noindent
Today (\today) the rate of exchange between the British pound
and the American dollar is \pounds 1 = \$1.63, an increase of
1\% over yesterday.
\end{document}

To globally change the paragraph indenting, you can change
the default for this directly:

                                                   (samp2.tex)
\documentclass{article}
\begin{document}
\setlength{\parindent}{0.5in}
Today (\today) the rate of exchange between the British pound
and the American dollar is \pounds 1 = \$1.63, an increase of
1\% over yesterday.
\end{document}

This will now indent all paragraphs by 0.5 inches.  To remove
paragraph indenting, just set this parameter to zero.

Latex ignores the carraige returns at the ends of each line
in the input file.  It also ignores extra blanks; it only
considers the first blank.  New paragraphs are defined by
adding a blank line between blocks of text.


EXAMPLE WITH EQUATIONS

                                                     (samp3.tex)
\documentclass{article}
\begin{document}
\setlength{\parindent}{0.0in}

The function $X(p)$ is more nicely behaved than $T(X)$ since it does not
cross itself (there is a single value of $X$ for each value of $p$), but
the inverse function $p(x)$ is multi valued.  An even nicer function is
the combination
\begin{equation}
\tau(p) = T(p) - pX(p),
\end{equation}
where $\tau$ is called the {\it delay time}.  It can be calculated very
simply:
\begin{equation}
\tau(p) = 2 \int_0^{z_p} \left[ {u^2 \over {(u^2-p^2)^{1/2}}} -
  {p^2 \over {(u^2-p^2)^{1/2}}} \right] \, dz
\end{equation}
or
\begin{eqnarray}
\tau(p) &=& 2 \int_0^{z_p} (u^2-p^2)^{1/2} \, dz \\
        &=& 2 \int_0^{z_p} \eta(z) \, dz
\end{eqnarray}
where $\eta$ is the vertical slowness.

\end{document}


Note that equations within the text are enclosed with $ signs.
\begin{equation} and \end{equation} are used to put the equation
on a separate line.  Variables within the equations are automatically
put into italics.  Greek letters are defined as \tau, \eta, etc.
Equations are automatically numbered (this can be changed if desired).
Subscripts are defined with the underscore (_), superscripts with the
carat (^).  Fractions are written as, for example, {x \over y}. 
\int is for the integral symbol; note how the limits are written.
Curly brackets are used to separate things--they do not appear
in the typeset version.

The \begin{eqnarray} section is used to align the = signs in
the two lines of equations.  Note that &=& is used to define
what it is that is being aligned.  Every line except the last
line has a carraige return (\\).  Although TeX generally does
an excellent job of spacing equations, sometimes some fine
tuning will help.  In this case \, is used to place a tiny
amount of space before the dz.  


CHANGING THE DEFAULT PARAMETERS


FONT SIZE

There is a standard font size declared for each document class.
In most cases this is Roman 10 pt.  One easy way to change the
size is with the following commands, arranged in increasing
order of size:

\tiny
\scriptsize
\footnotesize
\small
\normalsize
\large
\Large
\LARGE
\huge
\Huge

FONT ATTRIBUTES

\itshape  =  switch to italics
\slshape  =  switch to slanted font
\upshape  =  switch to upright (normal) font

\bfseries  =  switch to bold
\mdseries  =  switch (back) to regular weight

These commands can be invoked in several different
ways to put "in situ"  in italics and then return to 
normal font:

\itshape in situ \upshape

OR

{\itshape in situ}

OR

\begin{itshape}
in situ
\end{itshape}

These different options also apply to the font sizes listed
above.

Here is an example of how these options can be used:

                                                (samp4.tex)
\documentclass{article}
\begin{document}

Let's test different ways to say \itshape in situ \upshape
in italics.  There are several different ways to say
{\itshape in situ} in italics; indeed 
\begin{itshape}
in situ
\end{itshape}
can be written in italics in at least three different ways.

Next let's experiment with {\large large}, {\Large Large},
and {\LARGE LARGE} type, as well as {\small small}, 
{\footnotesize footnotesize}, and {\scriptsize scriptsize}
type.

\end{document}


LINE SPACING  

There is a default line spacing created whenever a new font is 
selected.  Here are examples of two different ways that this 
can be changed:

\setlength{\baselineskip}{10pt}   Change line spacing to 10 point
                                  (single spacing for 10pt font).

\renewcommand{\baselinestretch}{2}   Change normal (single) line spacing 
                                     by a factor of 2.  This will result
                                     in double spacing.  This must be
                                     called before \begindocument or before
                                     a new font declaration.

Here is an example:
                                                   (samp5.tex)
\documentclass{article}
\begin{document}
\setlength{\baselineskip}{20pt}
Today (\today) the rate of exchange between the British pound
and the American dollar is \pounds 1 = \$1.63, an increase of
1\% over yesterday.  Let's write one more line here so that we
get up to three lines and can see the spacing better.
\end{document}


INCLUDING GRAPHICS

There are some differences in the way different versions of
LaTeX handle graphics.  Many versions permit you to embed
EPS files but TeXShop requires PDF files, at least in the
standard version.  Fortunately, there are many ways to convert
files to PDF, including an option within the Mac print command.

Here is an example of including a pdf file:

                                                    (samp6.tex)
\documentclass{article}
\usepackage{graphicx}
\begin{document}
\setlength{\baselineskip}{20pt}
We are now going to show how to embed a Postscript file into
a LaTex document.  This is an example plot that can be
windowed and positioned using the "viewport" option within
the includegraphics commmand.  This specifies (x1,y1,x2,y2)
exactly what part of the page will be windowed and displayed.
(NOTE:  For Sun LaTeX, replace "viewport" with "bb" for bounding 
box)

\begin{figure}[h]
\begin{center}
\includegraphics[viewport=2in 2.4in 7in 7.5in, scale=0.7]{plot1.pdf}
\end{center}
\caption{Here is the caption for this plot.  This will be automatically
positioned below the plot.}
\end{figure}

And then here is some more text to show where the next block of text
will appear.  Blah, blah, blah...
\end{document}


Note that the graphicx package is loaded with the \usepackage{graphicx}
command at the start of the file.  

The \begin{figure} macro has various options for where the figure
will be positioned, including at the present location in the text, 
or at the top or bottom of the page.  The plot is windowed using
the viewport= option and scaled to 0.7 times its original size.  Figures
are automatically numbered; users have control over the starting
figure number.


WANT TO KNOW MORE?

Check out David McMillan's great Latex example file, ex.tex, which
you can find on the class web site or on the Suns in
~shearer/CLASS/COMP/LATEX or via anonymous ftp
to mahi.ucsd.edu in the pub/239 directory.  The accompanying files
psfig.tex, hobbes.ps, and gnufig.tex are also included there.  NOTE:
This file was designed for Sun LaTeX; not all of the figures will
appear on the Mac unless some of the graphics input commands are changed to
the TeXShop standard.

A good Latex reference book is:

Kopka, H., and P.W. Daly, A Guide to Latex 2e, Addison-Wesley,
  New York, 1995.