How do I write $\sim$ approximately with the correct spacing using siunitx?
Since version 2.1 siunitx
supports so called comparators
such as <
, =
, >
and also \approx
and \sim
. In version 2.6 the spacing for these was fixed such that
\SI{\sim 200}{\kelvin}
now gives exactly what you want.
See also input-comparators
on p. 21 of the siunitx
documentation.
MWE: compare this solution (first line) to your desired output (second line)
\documentclass{article}
\usepackage{siunitx}
\begin{document}
The temperature is \SI{\sim 200}{\kelvin}.
The temperature is $\sim$\SI{200}{\kelvin}.
\end{document}
~
is a relational symbol and should be used such. Further you can use \SI
macro inside the math mode. Hence, the correct way is
\documentclass{minimal}
\usepackage[detect-all]{siunitx}
\begin{document}
The temperature is $\sim\SI{200}{\kelvin}$.
\end{document}