# Match upper horizontal line of two fractions with different roots

I'm learning LaTeX and encountered a problem which I'm not able to solve after reading several related problems (e.g.: Align \sqrt with baseline of other mathematical input).

I will present my actual problem:

$\left(1 - \frac{\sqrt{2}}{π}\sqrt[4]{\frac{R_\text{out}}{R_\text{l}}}\right)$


I use XeLaTeX (MikTeX 2.9) with the XITS fonts, amsmath loaded.

As you can see the topmost drawn line of the roots are not alligned. I think that this occurs because Rout generates another height for the box on which the drawing of the root depends. I would like to 'align' the top lines of the roots (preferably in a way that the second fraction root is on the same level as the single root on the left).

\strut \mathstrut \vphantom[ ]


I am not sure if for this problem \smash or \mathclap could help. I really need a new input because sadly I can't solve the problem by myself :-(

• Welcome to TeX.SX! I'm not sure you really want this. – egreg Nov 8 '13 at 0:05
• Using 2\vphantom{R_\text{out}} should do it, but may look unsightly. – Werner Nov 8 '13 at 0:40
• @egreg: But don't you agree that it would look better if the top of the second root were a bit lower and shorter such that it does not touch the right bracket? And another reason is that I have seen it in a manual were it looks much better when the roots are on the same height (top drawn line). – Red Pencil Nov 8 '13 at 13:29

You can try removing the depth of the denominator:

\documentclass{article}
\usepackage{amsmath}
\usepackage{unicode-math}
\setmainfont{TeX Gyre Termes}
\setmathfont{XITS Math}

\begin{document}

$\left( 1 - \frac{\sqrt{2}}{π} \sqrt[4]{\frac{R_\text{out}}{R_\text{l}}} \,\right)$

$\left( 1 - \frac{\sqrt{2}}{π} \sqrt[4]{\frac{R_\text{out}}{R{\smash{_\text{l}}}}} \,\right)$

\end{document}


However, I don't find particularly bad the first realization. The most important adjustment is the thin space \, before \right).

• Is is just me or is the line in the left fraction thicker than the one on the right? – daleif Nov 8 '13 at 14:41
• @daleif: I was thinking the same thing. Are they maybe not aligned!? -so that the rendering creates thickness difference. – hpekristiansen Nov 8 '13 at 14:48
• @daleif Yes, it is. It doesn't happen with LuaLaTeX. – egreg Nov 8 '13 at 14:54
• Thank you very much! I tried many things and I might be able to cover things in just one line or if they have the same style but this 2 fractions where one root covers both I wasn't able to solve. Yes I also noticed that the style of the line change sometimes (also the top line of the root is thicker in the second root (at least on my pc). In case of optimal visual output consistency is therefore XeLaTeX not good enough? – Red Pencil Nov 8 '13 at 15:20