my Latex and Tex4ht cheat sheet

\documentclass{article}
\usepackage{luacode}
\usepackage{amsmath}
%------------------------
\begin{luacode}
function simplify(a,b)
local function gcd(a,b)
if b ~= 0 then
return gcd(b, a % b)
else
return math.abs(a)
end
end
t = gcd(a, b)
tex.print("\\frac{"..a/t.."}{"..b/t.."}")
end
\end{luacode}
\newcommand\simplify[2]{\directlua{simplify(#1,#2) }}%
%-------------------
\begin{document}
\noindent Can I make \LaTeX{} reduce a fraction automatically?\\[\baselineskip]
For example, I would like the fraction
\begin{equation*}
\frac{278\,922}{74\,088}
\end{equation*}
to be reduced to
\begin{equation*}
\simplify{278922}{74088}
\end{equation*}
\end{document}
The output of the above is
Can I make LATEX reduce a fraction automatically?
For example, I would like the fraction
to be reduced to
278 922
74 088
6641
1764
2.43.3 read CVS field to Latex table
This uses lua function to read the specific field in the CVS file. For example, given this CVS file in the directory
42