# LaTeX compilation problem [duplicate]

I am getting this while trying to compile literally my first document

This is pdfTeX, Version 3.14159265-2.6-1.40.16 (TeX Live 2015) (preloaded format=latex)
restricted \write18 enabled.
entering extended mode
(./t1.tex
LaTeX2e <2015/01/01>
Babel <3.9l> and hyphenation patterns for 79 languages loaded.
(/usr/local/texlive/2015/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/local/texlive/2015/texmf-dist/tex/latex/base/size10.clo)) (./t1.aux)
! Undefined control sequence.
l.6 \latex

?

• Welcome to TeX.SX! The command is either \LaTeX or \LaTeXe. You should show us the document t1.tex actually. – user31729 Jul 10 '16 at 10:22
• Please add a MWE so we can try it out for ourselves. From the error message it seems you use a command that has not been defined -- that is \latex. Please keep in mind that commands are case sensitive and you probably wanted to use \LaTeX. – HATEthePLOT Jul 10 '16 at 10:24
• Having the command \LaTeX etc that early in the document looks strange. It should occur after \begin{document}, not before (and spelled correctly, of course) – user31729 Jul 10 '16 at 10:29
• @ChristianHupfer It's on line 6, apparently, and is after \begin{document} (based on (./t1.aux)). – Joseph Wright Jul 10 '16 at 10:49
• @JosephWright: True, I didn't notice the .aux file: Thanks – user31729 Jul 10 '16 at 15:10

Both TeX and LaTeX are case-sensitive, i.e. it matters whether a command is written with uppercase or lower case letters.

Most likely, the command \LaTeX was intended, but was spelled as \latex which is wrong (unless somebody defines this command)

So out of the 32 possible variants of \latex, \Latex, \lATeX etc. only \LaTeX is correct ;-)

Please note that there is a special \LaTeXe command to output the LaTeX2e variant.

The example below shows also the difference between the font size command \huge and \Huge, i.e. where lowercase and uppercase forms provide significantly different output.

\documentclass{article}

\begin{document}
\huge
\LaTeX\ is very nice,
\LaTeXe\ is very nice too, but
\LaTeX3 is yet to come!

\Huge
\LaTeX\ is very nice,
\LaTeXe\ is very nice too, but
\LaTeX3 is yet to come!

\end{document}