# [Tex/LaTex] Sqrt with fraction in root argument

amsmathmath-mode

Possible Duplicate:
Nice-looking p-th roots

How can I move the root higher for this formula ? The fraction in the root is typeset to low:

\documentclass{minimal}
\begin{document}

$\sqrt[\frac{1}{3}]{\frac{4}{4.2}}$

\end{document}


the result of the document is

\documentclass{article}
\usepackage{amsmath}
\begin{document}

$\sqrt[\leftroot{-2}\uproot{5}\frac{1}{3}]{\frac{4}{4.2}}$

\end{document}


Unit for the macros is mu (mathunit 1mu=1/18em)

See also page 59 of mathmode document -> texdoc mathmode