Cfrgtkky

In decoration, second mark coordinate is not recognized:

  draw[thick,red,zigzag,postaction={

    decoration={

        markings,

        mark=at position 0.7 with coordinate (x);

        mark=at position 0.5 with coordinate (z); %unable to recognize z

    },

    decorate

  }] (-2,0) coordinate(a) -- (2,0) coordinate(b);

The MWE is as follows:

documentclass{article}

usepackage{tikz}

usetikzlibrary{decorations.pathmorphing}

usetikzlibrary{decorations.markings}

usetikzlibrary{calc}

usetikzlibrary{positioning}

tikzset{zigzag/.style={decorate,decoration=zigzag}}

begin{document}

begin{tikzpicture}

  coordinate (c) at (0,-2);

  coordinate (d) at (4,-2);

  coordinate (e) at (2,-4);

  draw[thick,red,zigzag,postaction={

    decoration={

        markings,

        mark=at position 0.7 with coordinate (x);

        mark=at position 0.5 with coordinate (z); %unable to recognize z

    },

    decorate

  }] (-2,0) coordinate(a) -- (2,0) coordinate(b);



  draw[thick,fill=blue!20] (c) -- (b) -- (d) -- (e) -- cycle;

  draw[thick,postaction={

    decoration={

        markings,

        mark = at position 0.7 with coordinate (y);

    },

    decorate

  }] (a) -- (c);

  draw[thick,red,dashed] (x) -- (y);



  node[above = 10ex of z,red] (sn) {singularity};

end{tikzpicture}

end{document} 

When I compile this code using PDFLaTeX, I get the following:

! Package pgf Error: No shape named z is known.



See the pgf package documentation for explanation.

Type  H <return>  for immediate help.

 ...                                              



l.32   node[above = 10ex of z,red]

                                    (sn) {singularity};

? 

Please guide me where I am going wrong.

You have to separate options by comma. It's also a good idea to put complex arguments in braces.

documentclass{article}

usepackage{tikz}

usetikzlibrary{decorations.pathmorphing}

usetikzlibrary{decorations.markings}

usetikzlibrary{calc}

usetikzlibrary{positioning}

tikzset{zigzag/.style={decorate,decoration=zigzag}}

begin{document}

begin{tikzpicture}

  coordinate (c) at (0,-2);

  coordinate (d) at (4,-2);

  coordinate (e) at (2,-4);

  draw[thick,red,zigzag,postaction={

    decoration={

        markings,

        mark=at position 0.7 with {coordinate (x);},

        mark=at position 0.5 with {coordinate (z);},

    },

    decorate

  }] (-2,0) coordinate(a) -- (2,0) coordinate(b);



  draw[thick,fill=blue!20] (c) -- (b) -- (d) -- (e) -- cycle;

  draw[thick,postaction={

    decoration={

        markings,

        mark = at position 0.7 with coordinate (y);

    },

    decorate

  }] (a) -- (c);

  draw[thick,red,dashed] (x) -- (y);



  node[above = 10ex of z,red] (sn) {singularity};

end{tikzpicture}

end{document}