\input{preamble-standalone.ltx} \begin{document} % Ex. No. 93 (Section 13.1.2 : Horizontal line and value calculated by \tkzname{xfp} ) \begin{tikzpicture} \tkzInit[xmin=-3,xmax=3,ymin=-2,ymax=1.5] \foreach\v in {-1,1} {\tkzHLine[color=red]{\v*pi/2}} \tkzDrawY \tkzAxeX[trig=2] \tkzLabelY \end{tikzpicture} \end{document}