Vfrdtyky

I would like to define a variable j in a loop foreach i in { 2, 4, 6} and use j to labels of the nodes.

Here is my code:

documentclass{standalone}

usepackage{balance,complexity,pgfplots,tikz,tikz-3dplot}

usetikzlibrary{calc}



begin{document}





begin{tikzpicture}[scale=0.4]



        def half {0.5};



        foreach i in { 2, 4, 6}

        {

            def j {i*half};

            node[draw=none] at (i,0) {$X_{j}$};

            node[draw=none] at (-i,0) {$X'_{j}$};

        }





end{tikzpicture}

end{document}

I would like to get this output:

Instead, I get this:

How can I use mathematical operators to modify the label of a node?

Use the pgfmath macros (pgfmathsetmacro for float calculations and pgfmathtruncatemacro if you only want the integer part).

documentclass{standalone}

usepackage{tikz}



begin{document}





begin{tikzpicture}[scale=0.4]

        pgfmathsetmacrohalf {0.5};

        foreach i in { 2, 4, 6}

        {

            pgfmathtruncatemacroj{i*half};

            node[draw=none] at (i,0) {$X_{j}$};

            node[draw=none] at (-i,0) {$X'_{j}$};

        }

end{tikzpicture}

end{document}

You can do the calculations within the foreach loop with

foreach i [evaluate=i as moitie using int(i/2)] in { 2, 4, 6} 

see page 904 of manual 3.0.1a.

documentclass{standalone}

usepackage{tikz}



begin{document}

begin{tikzpicture}[scale=0.4]

foreach i [evaluate=i as moitie using int(i/2)] in { 2, 4, 6}

        {

            node[draw=none] at (i,0) {$X_{moitie}$};

            node[draw=none] at (-i,0) {$X'_{moitie}$};

        }

end{tikzpicture}

end{document}