The solution consists essentially in writing

```
\usepackage{fancyvrb,standalone}
\newenvironment{rtf-code}
{\VerbatimOut{temporary.rtf}}
{\endVerbatimOut\immediate\write18{rtf2latex2e temporary.rtf}%
\input{temporary}}
```

and calling `pdflatex -shell-escape`

.

Similar to what I wrote in Help me to write Long LaTeX equations fast with colours and possibly with other aids, and what others have wrote here, the only way to debug these really is to break them down and re write them in a clearer manner.

I don't think there is going to be *one* generic method that will work for all types of problem.
But for this specific case, the equation as is yields the following message:

Missing } inserted.

This particular error usually means that the curly braces are not matched.
So the next thing I do is to use a feature that I think is available in most LaTeX Editors/IDEs (I know it is in TeXShop and TeXworks), and click on the opening curly brace to get to locate the matching closing curly brace.

So, the first one matches, and so do the next few:

Once you get to the `\sqrt`

after the third equal sign, you find that there is no matching closing brace:

So that tells you where the problem is. Adding the closing brace fixes the syntax, and you are done with the debugging:

So, all that is now left are the cosmetic aspects. The integral sign seems rather small.
So you can either load the `bigints`

package as per Big integral sign, but I found the results better with
`\mathlarger`

.

## Notes:

- I thought that this equation should be in display mode, but resulted in the large square root being too vertical, which did not look good to me, so left it in inline mode
- Also, not sure why you have braces around the
`(t)`

, but I left them as is.

Then, adding some new lines and spacing the code to make it more readable we have:

```
\documentclass{article}
\usepackage{amsmath}
\usepackage{relsize}
\newcommand{\intL}{\mathlarger{\mathlarger\int}}
\begin{document}
$\tau
= \intL\frac{dt}{\gamma}
= \intL\sqrt{1-\frac{v(t)^2}{c^2}}dt
= \intL\sqrt{
1 - \frac{1}{c^2}
\left(
\left(\frac{dx}{dt}\right)^2
+ \left(\frac{dy}{dt}\right)^2
+ \left(\frac{dz}{dt}\right)^2
\right)
} dt$
\end{document}
```

If you are typing these types of equations often, you might want to consider defining macro such as the `\D{}`

below to make your code even more readable and easier to debug.
Furthermore, the `d`

in `dt`

should be upright.
So with those changes you get:

```
\documentclass{article}
\usepackage{amsmath}
\usepackage{relsize}
\newcommand{\intL}{\mathlarger{\mathlarger{\int}}}
\newcommand{\dd}[1]{\mathrm{d}#1}
\newcommand{\D}[1]{\left(\frac{\dd{#1}}{\dd{t}}\right)}
\begin{document}
$\tau
= \intL\frac{\dd{t}}{\gamma}
= \intL\sqrt{1-\frac{v(t)^2}{c^2}}\dd{t}
= \intL\sqrt{
1 - \frac{1}{c^2}
\left( \D{x}^2 + \D{y}^2 + \D{z}^2 \right)
} \dd{t}$
\end{document}
```

## Best Answer

Although it has ben mentioned in some other posts, latexindent was missing here.

`latexindent`

is aIt can be used from command line or through

`arara`

A before-and-after example stolen from its documentation: