Consider the following simple MWE:
\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
\draw(0,0) -- (3,3);
\pgfmathparse{2+1}
\draw[red] (0,0) -- (3,\pgfmathresult);
\end{tikzpicture}
\end{document}
I expect to have, as an output, one red line, however this is the result that I get:

So, is it a bug, feature, or simply me doing something wrong?
\pgfmathresultchanges at\draw[red]. Try\pgfmathsetmacro\temp{2+1}\draw[red] (0,0) -- (3,\temp);instead. – jub0bs Mar 25 '14 at 15:34tikzmaintainers an email, or open an issue on the dedicated page... – jub0bs Mar 25 '14 at 19:22