# Circuitikz doesn't recognize units

For example when I use \ohm or \micro it throws an error. For example, in the MWE:

\documentclass{article}
\usepackage{circuitikz}
\begin{document}
\begin{circuitikz} \draw
(0,0) to [C=$100\ohm$](2,0)
;
\end{circuitikz}


It produces the error:

"Undefined control sequence:    \pgfk@/tikz/circuitikz/bipole/label/name ...0\ohm :
(0,0) to [C=$100\ohm$](2,0)"


I updated the package and it didn't help.

-

You have to load circuitikz with the siunitx option.

Also, the correct syntax is |component| = |value|<|unit|>. The unit macro needs to be surrounded by < and >. The expression may not be put in math mode by surrounding it with $. Here's an example: \documentclass{article} \usepackage[siunitx]{circuitikz} \begin{document} \begin{circuitikz} \draw (0,0) to [R=1<\ohm>] (2,0); \end{circuitikz} \end{document}  - Thanks. However, as I wrote down, I would have preferred to use the simpler format as in pastebin.com/w8f4Pc9v without the '<>' is it obsolete? – Andro Oct 19 '11 at 5:45 That syntax was never officially supported, as I understand it. If you use ConTeXt, circuitikz defines a number of units and a mock \SI command so your document still compiles. The unit definitions are of the form \def\ohm{\Omega}, which then of course makes it possible to write $100\ohm$ (in that case you need to have the $ signs). You can find the list of definitions in the file t-circuitikz.tex, if you want to copy them into your document. However, I would recommend sticking with the official syntax: It's the same number of keystrokes, and siunitx is a very powerful package. –  Jake Oct 19 '11 at 6:14

You should use the siunitx package for the units:

\documentclass{article}
\usepackage{tikz}%
\usepackage{circuitikz}
\usepackage{siunitx}

\begin{document}
\begin{circuitikz} \draw
(0,0) to [C=$\SI{100}{\ohm}$](2,0);
\end{circuitikz}
\end{document}​

-
Thanks. So I understand that text in the following format: pastebin.com/w8f4Pc9v is now obsolete? it seems simpler than writing \SI{}{} every time –  Andro Oct 19 '11 at 5:42
I would recommend you figure out how you want to handle units in general and use that method consistently thruout. –  Peter Grill Oct 19 '11 at 15:04