One way to go is the XePersian package which has excelent support for both right-to-left and left-to-righ texts. Although it is primarily developed for Persian language, it can be used for Arabic text as well, since both languages share the same alphabet. It is possible to be used with memoir
and in case you have function plots and other vector graphics, it works fine with tikz
. Here is a minimal example of Arabic text in a memoir
documentclass with short vowels and an inline Latin text:
\documentclass{memoir}
\pagestyle{empty}
\usepackage{xepersian}
\begin{document}
السّلام عَليكم
\lr{Peace to you too!}
\end{document}

You can have longer passages of English (latin letters in general) using latin
environment. Note that you should compile this XePersian
with XeLateX
.
There is also a package called ArabTex but I'm not familiar with that.