Node: User preamble, Previous: Default preamble, Up: LaTeX preamble

#### 7.2.2 User preamble

You tell PP3 where your own preamble is with the filename parameter ``latex_preamble`' in the input script, for example:

```     filename latex_preamble mypreamble.tex
```

The file `mypreamble.tex` contains your LaTeX preamble macros and must reside in the current directory, or in another directory where TeX looks for its files.

The following is the contents of the file `wiki.tex` of the PP3 distribution. It is the original user LaTeX preamble that was used for the Wikipedia Project, see Successful use of PP3.

```     01   \usepackage{amsmath}
02   \usepackage[T1]{fontenc}
03   \IfFileExists{eulervm.sty}{\usepackage{eulervm}}{}
04   \usepackage{relsize}
05   \IfFileExists{t1pmy.fd}{
06     \renewcommand*{\sfdefault}{pmy}
07   }{
08     \renewcommand*{\sfdefault}{phv}
09   }
10   \renewcommand{\Messier}[1]{\footnotesize{\scriptsize M}\,#1}
11   \renewcommand{\NGC}[1]{\footnotesize{\scriptsize NGC}\,#1}
12   \renewcommand{\IC}[1]{\footnotesize{\scriptsize IC}\,#1}
13   \renewcommand{\FlexLabel}[1]{{\bfseries #1}}
14   \renewcommand{\TicMark}[1]{{\mdseries\scriptsize\mathversion{normal} #1}}
15   \AtBeginDocument{\sffamily\boldmath}
```

And this is what it does:

Line 1
includes the AMSMath package which provides additional macros that can be useful in text labels. You can include almost arbitrary LaTeX packages.
Line 2
activates the so-called T1 font encoding. It's not important to know what this means, but it is recommended and doesn't do any harm.
Line 3
activates nicer Greek letters. Well, your taste may be different. This `\IfFileExists` thing tests whether the package is available on the current computer. The package is included only if it exists.
Line 4
enables the macro `\smaller` which can be very useful in text labels. It reduces the current font size. For example I can say
```          set_label_text LEO 32 "\\smaller Regulus"
```

Lines 5–9
test whether the font Myriad is available on the current computer, and if it does, it makes it the new standard sans-serif font. Else it uses Helvetica for that.
Lines 10–14
re-defines various LaTeX hooks in order to have nicer looking automatic labels, see LaTeX hooks.
Line 15
switches to sans-serif font (Myriad/Helvetica) with `\sffamily` and to bold Greek letters with `\boldmath`.