Cfrgtkky

I have a pgfplot and the labels in the x axis are not centered as I expected and this is because one of them is higher than the other because of the superscript.

documentclass{article}  % Use the "Thesis" style, based on the ECS Thesis style by Steve Gunn



usepackage{pgfplots}



begin{document}



    begin{tikzpicture}

        begin{axis}[

            ytick={empty},

            ytick={},

            xticklabels={$u_{n+1}^{}$,$u_{n+1}^{0}$},

            xtick={0,4},

            yticklabels={$r(u_{n+1}^{}) = 0$,$r(u_{n+1}^{0})>0$},

            ytick={-2,2},

            domain=-2:6,

            samples=55,

            scaled ticks=false,

            ymax=10,

            ymin=-5,

            xtick distance={60},

            ]

            %addplot+[no marks,thick] {-5*(x-1)*(x)*(x-2)};

            addplot[smooth,thick]

                coordinates{

                    (-1.9,9.9) (-1,0) (0,-2) 

                    (1,0)(3,4)(4,2)

                    (5,4)(6,10)

                };

            draw[dashed] (axis cs:0,-5) -- (axis cs:0,-2);

            draw[dashed] (axis cs:4,-5) -- (axis cs:4,2);

            draw[dashed] (axis cs:-3,-2) -- (axis cs:0,-2);

            draw[dashed] (axis cs:-3,2) -- (axis cs:4,2);

            node[circle,draw=black,fill=black,scale=0.8] at (axis cs:0,-2) {};

            node[circle,draw=black,fill=black,scale=0.8] at (axis cs:4,2) {};

        end{axis}

    end{tikzpicture}



end{document}

And a zoom of the axis:

How can I do to center the letter u to the same distance ?

On my machine adding xticklabel style={text height=2ex} works.

documentclass{article}  % Use the "Thesis" style, based on the ECS Thesis style by Steve Gunn



usepackage{pgfplots}



begin{document}



    begin{tikzpicture}

        begin{axis}[

            ytick={empty},

            ytick={},

            xticklabels={$u_{n+1}^{}$,$u_{n+1}^{0}$},

            xtick={0,4},

            yticklabels={$r(u_{n+1}^{}) = 0$,$r(u_{n+1}^{0})>0$},

            xticklabel style={text height=2ex},

            ytick={-2,2},

            domain=-2:6,

            samples=55,

            scaled ticks=false,

            ymax=10,

            ymin=-5,

            xtick distance={60},

            ]

            %addplot+[no marks,thick] {-5*(x-1)*(x)*(x-2)};

            addplot[smooth,thick]

                coordinates{

                    (-1.9,9.9) (-1,0) (0,-2) 

                    (1,0)(3,4)(4,2)

                    (5,4)(6,10)

                };

            draw[dashed] (axis cs:0,-5) -- (axis cs:0,-2);

            draw[dashed] (axis cs:4,-5) -- (axis cs:4,2);

            draw[dashed] (axis cs:-3,-2) -- (axis cs:0,-2);

            draw[dashed] (axis cs:-3,2) -- (axis cs:4,2);

            node[circle,draw=black,fill=black,scale=0.8] at (axis cs:0,-2) {};

            node[circle,draw=black,fill=black,scale=0.8] at (axis cs:4,2) {};

        end{axis}

    end{tikzpicture}



end{document}

To overcome this there exists the option typeset ticklabels with strut. Simply add it to the axis options and you receive the expected result.

% used PGFPlots v1.16

documentclass[border=5pt]{standalone}

usepackage{pgfplots}

begin{document}

begin{tikzpicture}

    begin{axis}[

        xtick={0,4},

        xticklabels={$u_{n+1}^{}$,$u_{n+1}^{0}$},

        ymin=-5,

        ymax=10,

        ytick={-2,2},

        yticklabels={$r(u_{n+1}^{}) = 0$,$r(u_{n+1}^{0})>0$},

        typeset ticklabels with strut,      % <-- added

    ]

        addplot [smooth,thick] coordinates {

            (-1.9,9.9) (-1,0) (0,-2)

            (1,0)(3,4)(4,2)

            (5,4)(6,10)

        };

        draw [dashed] (axis cs:0,-5) -- (axis cs:0,-2);

        draw [dashed] (axis cs:4,-5) -- (axis cs:4,2);

        draw [dashed] (axis cs:-3,-2) -- (axis cs:0,-2);

        draw [dashed] (axis cs:-3,2) -- (axis cs:4,2);

        node [circle,draw=black,fill=black,scale=0.8] at (axis cs:0,-2) {};

        node [circle,draw=black,fill=black,scale=0.8] at (axis cs:4,2) {};

    end{axis}

end{tikzpicture}

end{document}