Hi,

I don't know if this is a bug or a feature, but consider the following
test file:

#+BEGIN_SRC Org
#+TITLE: Fails when exporting
#+TITLE: Fails when exporting

* Instructions							   :noexport:

  1. Start =emacs -q=
  2. <<p2>> Run \src_emacs-lisp{(org-preview-latex-fragment)}
     - WORKS
  3. <<p3>> Run \src_emacs-lisp{(org-latex-export-to-pdf)} =./test.pdf=
     - FAILS

  [[p2]] works when [[p3]] fails because `org-format-latex-header`
  loads =amsmath=, but Org LaTeX export doesn't.  Why I don't know.

  *Proposal: Replace amstext with amsmath.*

* test
\begin{align}
x \mathcal{ABC}
\end{align}
#+END_SRC


The first patch adds amsmath as a dependency which fixes the above
bug.  According to my TeXLive it seems amstext is distributed with
amsmath, so I don't think that's an issue.  Increased load time?
Well, maybe.  I didn't test.

Will amstext be missed?  No, it's loaded by amsmath, currently line 120

     \RequirePackage{amstext}[1995/01/25]

The second patch removes the dependency on eucal.  Eucal provides an
alternative font for the mathcal macro.  Unless someone believes it's
better than the standard font, e.g. for small fonts, there is little
point in requiring it IMO.

We could also replace color with xcolor, which is the better
alternative, but I don't think it matters in this case and hence I
haven't provided a patch for that. 

–Rasmus