\sum caused \sqrt to not be slanted

Question

As shown in the MWE below, \sum (esp. when the index and lower/upper bounds are defined) is causing the slanty part of the sqrt sign to be not slanty. Is there a way to preserve it?

\documentclass{article}

\begin{document}

\[
\sqrt{{x^i}}
\]
\[
\sqrt{\sum_{i = 1}{x^i}}
\]
\[
\sqrt{\sum^{n}{x^i}}
\]
\[
\sqrt{\sum_{i = 1}^{n}{x^i}}
\]

\end{document}

Answer 1

If you look carefully you can see that the angle changes if the part below the root sign gets larger until it is vertical. Imho all math fonts will do it. So if you want a slant: make the content smaller, e.g. by using \nolimits:

\documentclass{article}

\begin{document}

\[
\sqrt{1+ \sqrt{1+ \sqrt{1 + \sqrt{1+ \sqrt{1+ \sqrt{1+x}}}}}} 
\]

\[
\sqrt{\sum\nolimits_{i = 1}^{n}{x^i}}
\]

\end{document}

Answer 2

The only math font package I know that has slanted surds at large sizes is mtpro2:

\documentclass{article}
\usepackage[lite]{mtpro2}

\begin{document}

\[
\SQRT{1+ \SQRT{1+ \SQRT{1 + \SQRT{1+ \SQRT{1+ \SQRT{1+x}}}}}}
\]

\[
\SQRT{\sum_{i = 1}^{n}{x^i}}
\]

\end{document}

Note that \SQRT should be used for this to work. Unfortunately, adapting this to other font families would be very complicated. The package changes all fonts to be Times like.

Answer 3

With MinionMath-Regular:

\documentclass{article}
\usepackage{unicode-math}
\setmathfont{MinionMath-Regular.otf}
\begin{document}

\[
  \sqrt{{x^i}}
\]
\[
  \sqrt{\sum_{i = 1}{x^i}}
\]
\[
  \sqrt{\sum^{n}{x^i}}
\]
\[
  \sqrt{\sum_{i = 1}^{n}{x^i}}
\]

\end{document}

Answer 4

Two suggestions:

• You could affix \nolimits to \sum, to force LateX to set the limits of summation to the side rather than above and below the summation symbol. That way, the surds will be noticeably less steep and their overall height will be much reduced, reducing their visual dominance. Of course, if you side-set the limits of summation, the formulas will take up more horizontal space. (I just noticed that this suggestion is also made in the second half of Ulrike's answer.)

• If you want to keep the limits of summation above and below the summation symbol, you could switch to using large parentheses and exponential notation to indicate that square roots are being taken. If you go this route, be sure to use \biggl( and \biggr) and not \left( and \right, as otherwise the parentheses would become too large from a typographic/aesthetic point of view.

\documentclass{article}
\begin{document}
\[
\sqrt{\sum_{i=1} x^i} \quad \sqrt{\sum_{i=1}^{n} x^i}
\quad\mbox{vs.}\quad
% use of "\nolimits"
\sqrt{\sum\nolimits_{i=1} x^i} \quad \sqrt{\sum\nolimits_{i=1}^{n} x^i}
\quad\mbox{vs.}\quad
% use of parenthetic notation
\biggl(\,\sum_{i=1} x^i \!\biggr)^{\!1/2} \quad 
\biggl(\,\sum_{i=1}^{n} x^i \!\biggr)^{\!1/2}
\]
\end{document}

Answer 5

We could do it, but it would be wrong.

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

\[
\sqrt{\sum_{i = 1}^{n}{x^i}}
\]
\[
\scalebox{2}{$\displaystyle\sqrt{\scalebox{0.5}{$\displaystyle\sum_{i = 1}^{n}{x^i}$}}$}
\]

\end{document}