test.tex

\documentclass[12pt]{article}
\newcommand{\Srf}{\sqrt{5}}
q
\begin{document}
LaTeX Access  test file:

LaTeX access processes many common mathematical symbols, for
example:
$$\sin^2\theta+\cos^2\theta=1$$
$$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$
$$\int_0^1 x^2\,dx=\frac{1}{3}$$
If a custom command is defined, then the preprocessor can be used to
convert it into its normal form before translation.  For example,
Use the preprocessor to have the following read correctly:
$$\Srf^4=25$$

The matrix processor enables the virtual navigation of matrices.
Highlight the contents of the below 4 by 4 matrix, (not including
the begin and end commands), and press the input matrix key:
$$M=\begin{pmatrix}
1 & 4 & 2 & 3\\
-8 & 7 & 6 & 5\\
0 & 0 & 0 & 1\\
2 & 4 & 3 & 8\\
\end{pmatrix}$$

\end{document}