Cfrgtkky

I've been scouring the web and the pgfplots manual trying to find an example of labelling different x-axis ticks with different Greek characters.
The closest i've found is using

    xticklabel={$pgfmathprintnumber{tick}sigma $},

    xtick={-3,-2,-1,0,1,2,3},

My full code for the plot is as follows

    pgfplotsset{width=7cm,compat=1.16}

    begin{center}

    begin{tikzpicture}[baseline]

    begin{axis}[

        axis lines=left,

        title={Standard Normal Distribution $Zsim Nleft ( 0,1 right )$},

        xlabel={$z$-score},

        ylabel={Probability},

        xticklabel={$pgfmathprintnumber{tick}sigma $},

        xtick={-3,-2,-1,0,1,2,3},

        ytick={0,0.1,0.2,0.3,0.4},

        ymax=0.5

        ]



        newcommandMU{0}

        newcommandSIGMA{1}

        addplot[

            domain=-4*SIGMA:4*SIGMA,

            samples=201,

            ]

            {exp(-(x-MU)^2 / 2 / SIGMA^2) / (SIGMA * sqrt(2*pi))};

    end{axis}

    end{tikzpicture}

    end{center}

But here it obviously just amends each xtick with a sigma next to the value.
What I want is for the xticks to read mu-3*sigma, mu-2*sigma, mu-sigma, mu etc etc.

Any ideas would be greatly appreciated.

Welcome to TeX.SE! Something like this?

documentclass{article}

usepackage{pgfplots}

begin{document}

pgfplotsset{width=12cm,compat=1.16}

begin{center}

begin{tikzpicture}[baseline]

begin{axis}[

    axis lines=left,

    title={Standard Normal Distribution $Zsim Nleft ( 0,1 right )$},

    xlabel={$z$-score},

    ylabel={Probability},

    xticklabel={$mupgfmathtruncatemacro{mytick}{int(tick)}

    ifnummytick=0

    else

    pgfmathparse{ifthenelse(tick<0,"","+")}

    pgfmathresultpgfmathprintnumber{tick}sigmafi $},

    xtick={-3,-2,-1,0,1,2,3},

    ytick={0,0.1,0.2,0.3,0.4},

    ymax=0.5

    ]



    newcommandMU{0}

    newcommandSIGMA{1}

    addplot[

        domain=-4*SIGMA:4*SIGMA,

        samples=201,

        ]

        {exp(-(x-MU)^2 / 2 / SIGMA^2) / (SIGMA * sqrt(2*pi))};

end{axis}

end{tikzpicture}

end{center}

end{document}

I made the plot a bit wider such that the now wider labels do not overlap. Alternatively, you may rotate them.