# Not all Math don't compile in express package

The following problem happens when I try to work with a package of a specific journal called Optics Express. You can get the relevant class in the OSA page.

The following text builds a proper PDF with PDFLaTeX:

\documentclass[10pt]{article}
\usepackage[OE]{express}
\usepackage{amsmath}
\begin{document}
$\frac{\pi}{\rho}$ text text
\end{document}


But the following code does not:

\documentclass[10pt]{article}
\usepackage[OE]{express}
\usepackage{amsmath}
\begin{document}
$\pi$
\end{document}


Most of the times the above file seems to be compiling, but in fact it doesn't. Even if you take the OSA example from the .zip file, and try to type $\pi$ in the text, it fails.

EDIT - Error Log: Shows consistently the following error:

Font rtxmi at 600 not found
==> Fatal error occurred, no output PDF file produced!


I don't have the faintest idea even where to begin looking for the answer. I use MikTex 2.9.4248, and I compile PDFLaTeX all the time, so I think it has something to do with the package.

Further Details: The PDFLatex fails straight away, while the DVI-PS-PDF produces a PDF, but without the $\pi$ symbol. Both newtxtext and newtxmath are not installed in my environment, nor are they available in my repository.

• The error message is pretty clear: The font rtxmi is not installed, it's not provided within the .zip file. It seems to be related with newtxmath, but I am not sure – user31729 Aug 1 '17 at 18:17
• I experience no problem compiling your code with pdflatex under MacTeX2017. Please tell us how you compile the tex file. Do you compile straight to pdf (with, say, pdflatex), do you try to go the -> dvi -> ps -> pdf route, or still something else? Please also tell us which TeX distribution (and which vintage) you employ. Finally, do tell us if the newtxtext and newtxmath packages are installed on your system. – Mico Aug 1 '17 at 18:20
• Are you really saying that using \pi within \frac{...}{...} works. i.e., the font is found, while using it directly doesn't work? – Herb Schulz Aug 1 '17 at 19:40
• @HerbSchulz That is possible. It will be using a different size for the fraction, I assume. – cfr Aug 2 '17 at 3:00
• Then something is very wrong with your current MikTeX installation! All I can suggest at this point is that you perform a full reinstallation from scratch, this time specifying that all packages be downloaded and installed. – Mico Aug 2 '17 at 11:11