# Break in square root line

I'm having a problem where the line that runs the top length of my square root sign is discontinuous.

$$N_t(\text{V})=\sqrt{\sum_{i=0}^{n}N_i^2}$$


Yields this...

Any ideas what's causing that broken line on the top of my root symbol??

• The left part is a character (or characters) from the font, the top part is a rule drawn by TeX, these are specified to be the same width but font hinting and pixel rounding and bad luck can mean that the join shows at some zoom levels. – David Carlisle Apr 1 '14 at 0:35
• So, am I just out of luck? – slowaudio Apr 1 '14 at 0:55
• @user2865011 In what sense? You are “out of luck”, but does it matter? As David pointed: “the join shows at some zoom levels”. – Manuel Apr 1 '14 at 1:06
• Using the old \surd symbol would make the join less obvious. – John Kormylo Apr 1 '14 at 4:52
• @JohnKormylo why? – David Carlisle Apr 1 '14 at 8:19

The idea is to overlay a thicker line over the two joined lines.

\documentclass{standalone}
\usepackage{mathtools}

\newsavebox{\mybox}
\newlength{\mywidth}
\newlength{\myheight}
\newlength{\myline}
\newlength{\myoffset}
\newcommand{\mysqrt}[1]%
{\setlength{\myline}{.1ex}%
\setlength{\myoffset}{.9em}
\savebox{\mybox}{$\displaystyle\sqrt{#1}$}%
\settoheight{\myheight}{\usebox{\mybox}}%
\settowidth{\mywidth}{\usebox{\mybox}}%