_           _                 
 | |_ ___  __| |____  ___ _   _ 
 | __/ _ \/ _` |_  / / _ \ | | |
 | ||  __/ (_| |/ / |  __/ |_| |
  \__\___|\__,_/___(_)___|\__,_|

Command line creation of SVG equation images from LaTeX

Create a file eq.tex as shown below:

\documentclass{standalone}
\begin{document}
$ \left( \frac{\frac{z^2+1}{z^2-1}}{13^{13}} \right) $
\end{document}

The following partly works, but the left and right brackets are not rendered correctly:

pdflatex -output-format dvi eq.tex
dvisvgm -TS4 eq.dvi

This renders the brackets correctly, but only outputs a PDF:

pdflatex eq.tex

This outputs a PDF cropped to the size of the equation:

xelatex eq.tex

The following command seems to produce a fully working SVG complete with brackets. I had to add the --no-fonts argument to dvisvgm to make it render the brackets. Previously they weren't shown for some reason. There was some kind of placeholder empty glyph remnant for each bracket.

xelatex -no-pdf eq.tex
dvisvgm --no-fonts -TS4 eq.xdv

A different approach:

\documentclass[convert={svg}]{standalone}

\usepackage{amsmath}
\begin{document}
$\left( \frac{\frac{z^2+1}{z^2-1}}{\frac{13^{13}}{x}} \right)$
\end{document}

pdflatex -shell-escape eq.tex

That yields an error (originating with Inkscape:

Unknown option --pdf-page=1
system returned with code 256

Class standalone Warning: Conversion unsuccessful!
(standalone)              There might be something wrong with your
(standalone)              conversation software or the file permissions!

...but you can run Inkscape directly with the --pages argument in place of the deprecated `--pdf-page, as shown below:

inkscape --pdf-poppler --export-type="svg" --pages=1 -o eq.svg eq.pdf

\documentclass{standalone}
\usepackage{amsmath}
\begin{document}
$\left( \frac{\frac{z^2+1}{z^2-1}}{\frac{13^{13}}{x}} \right)$
\end{document}

This works, but the resulting SVG is very small:

pdflatex eq.tex
inkscape --pdf-poppler --export-type="svg" --pages=1 -o eq.svg eq.pdf

I quite like this approach, but it produces an SVG that spans the full page width:

\documentclass[14pt]{extarticle}
\usepackage{amsmath}
\usepackage[active,tightpage]{preview}

% if you need the equation number, remove the asterix
\PreviewEnvironment{equation*}

% if you need paddings, adjust the following
\PreviewBorder=0pt

\begin{document}
\begin{equation*} % remove the asterix if you need the equation number
F(V, T) = E(V) + D(T)
\end{equation*} % remove the asterix if you need the equation number
\end{document}

Note that I used the extarticle document class so that I could set the font size to 14pt. The supported font sizes are 8pt, 9pt, 10pt, 11pt, 12pt, 14pt, 17pt and 20pt (see here).

pdflatex two.tex
inkscape --pdf-poppler --export-type="svg" --pages=1 -o two.svg two.pdf

This is the resulting SVG: