Bdtyktl

Is there a way to draw a dashed pattern between two nodes taking the middle point of these two nodes as the center point?

This is my code:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{amsthm,amsmath,amssymb,authblk,tikz,graphicx}

usetikzlibrary{shapes,decorations,circuits.logic.US,circuits.logic.IEC,fit,external}

tikzstyle{loosely dashed}=[dash pattern=on 4pt off 8pt]

tikzstyle{loosely dashed2}=[dash pattern=on 4pt off 8pt]



begin{document}



begin{figure}

    centering

    begin{tikzpicture}[every node/.style = {draw=none, text=black, circle, minimum size = 13mm, fill=gray!25}]

        path

        (0,3) node(y) {$Y$}

        (-1.5,0) node[draw, line width=1pt](x1) {$X_1$}

        (1.5,0) node[draw, line width=1pt](x2) {$X_2$};

        draw [line width=1pt,-,black] (y) -- (x1);

        draw [line width=1pt,-,black] (y) -- (x2);

        draw [line width=3pt,-,loosely dashed,black] (x1) to[bend right=40] (x2);

    end{tikzpicture}

end{figure}



end{document}

And the resulting figure:

It can clearly be seen that the dash from the X₁ node is longer than that from the X₂ node.

I want the right part of the dashed line to be the mirror image of the left part. Is there a way to do this (preferably regardless of the distance between the nodes, and the thickness or specific pattern of the line)?

There are standard answers, but all of them are very advanced and hard to understand. However, with markings one can "mirror" a half of the curve like this.

documentclass[tikz]{standalone}

usetikzlibrary{shapes,decorations,circuits.logic.US,circuits.logic.IEC,fit,external}

tikzstyle{loosely dashed}=[dash pattern=on 4pt off 8pt]

tikzstyle{loosely dashed2}=[dash pattern=on 4pt off 8pt]



begin{document}

    begin{tikzpicture}[every node/.style = {draw=none, text=black, circle, minimum size = 13mm, fill=gray!25}]

        path

        (0,3) node(y) {$Y$}

        (-1.5,0) node[draw, line width=1pt](x1) {$X_1$}

        (1.5,0) node[draw, line width=1pt](x2) {$X_2$};

        draw [line width=1pt,-,black] (y) -- (x1);

        draw [line width=1pt,-,black] (y) -- (x2);

        %draw [line width=3pt,-,loosely dashed,black] (x1.south east) to[bend right=40] (x2.south west);

        path [postaction={

            decorate,

            decoration={

                markings,

                mark=at position 0.5 with coordinate (mid);

            }

        }] (x1) to[bend right=40] (x2);

        draw[line width=3pt,-,loosely dashed] ([xshift=-4pt]mid) to[out=180,in=-40] (x1);

        draw[line width=3pt,-,loosely dashed] ([xshift=4pt]mid) to[out=0,in=-140] (x2);

    end{tikzpicture}

end{document}

Another way is to measure the path and then stretch the dash length a bit in such a way that the path ends with a full on. Please also note that tikzstyle is deprecated.

documentclass{article}

usepackage{tikz}

usetikzlibrary{decorations.markings}

tikzset{

    full dash/.style args={on #1 off #2}{

    decoration={

    markings,

    mark=at position 0 with {

      pgfmathsetmacro{mystretch}{((pgfdecoratedpathlength-#1)/(#1+#2))/int((pgfdecoratedpathlength-#1)/(#1+#2))}

      pgfmathsetmacro{myon}{#1*mystretch}

      xdefmyon{myon}

      pgfmathsetmacro{myoff}{#2*mystretch}

      xdefmyoff{myoff}

    },

  },

  preaction={decorate},draw=none,

  postaction={draw,dash pattern=on myon pt off myoff pt}

  },

}

begin{document}



begin{figure}

    centering

    begin{tikzpicture}[every node/.style = {draw=none, text=black, circle, minimum size = 13mm, fill=gray!25}]

        path

        (0,3) node(y) {$Y$}

        (-1.5,0) node[draw, line width=1pt](x1) {$X_1$}

        (1.5,0) node[draw, line width=1pt](x2) {$X_2$};

        draw [line width=1pt,-,black] (y) -- (x1);

        draw [line width=1pt,-,black] (y) -- (x2);

        draw [line width=3pt,-,full dash=on 3pt off 6pt,black] (x1) to[bend right=40] (x2);

    end{tikzpicture}

end{figure}



end{document}