TeXについて教えて

質問

LaTeX Equation Editorを使っていますが、うまく数式が出ず、困っています．

時に出たり出なかったりするので、原因が特定出来ません．HelpのGetting Startedにある
\sum_{i=0}^{n} {n \choose i} = 2^n
でまずErrorが出ます．

LaTeXでは全く正常に文章が書けます．

解決方法を教えて下さい．

回答No.1

Tacosan

使っている TeX のバージョン, LaTeX のバージョンと「出ているエラーメッセージ」くらいは書いてほしいなぁ.

補足

ptex2004v1を使っています．
単にF=maと入力したときのエラーメッセージは次の通りです．宜しくお願いします．

This is TeX, Version 3.14159 (Web2C 7.4.5) (format=latex 2004.3.10) 1 SEP 2006 21:01
**\scrollmode\input{equation.tex}
(./equation.tex

! LaTeX Error: \usepackage before \documentclass.

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...

l.2 \usepackage[dvips]{
color}
\usepackage may only appear in the document preamble, i.e.,
between \documentclass and \begin{document}.

! Undefined control sequence.
l.3 \color
[rgb]{0.000,0.000,0.000}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...

l.3 \color[
rgb]{0.000,0.000,0.000}
You're in trouble here. Try typing <return> to proceed.
If that doesn't work, type X <return> to quit.

Missing character: There is no [ in font nullfont!
．．．
Missing character: There is no 0 in font nullfont!
No file equation.aux.
\openout1 = `equation.aux'.

LaTeX Font Info: Checking defaults for OML/cmm/m/it on input line 4.
．．．
LaTeX Font Info: ... okay on input line 4.

! LaTeX Error: The font size command \normalsize is not defined:
there is probably something wrong with the class file.

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...

l.4 \begin{document}

Your command was ignored.
Type I <command> <return> to replace it with another command,
or <return> to continue without it.

LaTeX Font Info: External font `cmex10' loaded for size
(Font) <7> on input line 5.
LaTeX Font Info: External font `cmex10' loaded for size
(Font) <5> on input line 5.

! LaTeX Error: The font size command \normalsize is not defined:
there is probably something wrong with the class file.

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...

l.6 \end{document}

Your command was ignored.
Type I <command> <return> to replace it with another command,
or <return> to continue without it.

[1] (./equation.aux) )
Here is how much of TeX's memory you used:
9 strings out of 95847
108 string characters out of 1195582
44507 words of memory out of 1000001
3037 multiletter control sequences out of 10000+50000
3640 words of font info for 14 fonts, out of 500000 for 1000
14 hyphenation exceptions out of 1000
19i,4n,12p,64b,150s stack positions out of 1500i,500n,5000p,200000b,5000s

Output written on equation.dvi (1 page, 260 bytes).