# Is there a way to fix the following errors?

I am trying to compile a .tex file using pdflatex and I get the following two kinds of errors:

``````Package natbib Warning: Citation `give-citation' on page 14 undefined on input line 41.

! Undefined control sequence.
<argument> ...e \NAT@cmt \fi \if \relax \NAT@date \relax \else \NAT@@close \...
l.46 ... information is available \cite{}
``````

It works smoothly with pdflatex on my mac.

Another error that I get on this linux box (again using pdflatex) is:

`````` ! LaTeX Error: Unknown graphics extension: .eps.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
....
l.12 ...\includegraphics[width=4.2in]{tree.eps}
``````

These errors appear quite frequently, they are all over the document. Is it possible to fix them?

-
The `Undefined control sequence` is because a macro is not defined. Most likely one of your packages (`natbib` or a related one) is outdated. Simply update your LaTeX installation and try it again. Also have a look in the `log` file for warnings which sound like "package has been requested in version <...> but only version <...> was found" or similar.
The second error is because you are trying to use a EPS with `pdflatex` which doesn't support this format. Either convert this file to a PDF using e.g. the `epstopdf` program or you can load the `epstopdf` package to do this automatically. This however requires that the option `-shell-escape` is used.
And here the difference between the Mac and the Linux box might be that e.g. TeXShop defaults to enabling `\write18` (which allows external programs to be run); other systems/editor combinations might not allow this, even with the `epstopdf` package loaded. –  Alan Munn Feb 21 '11 at 0:00