How can I use pgfplots to generate a 2D coordinate system image

Question

I try to run the example given by pgfplots :

\documentclass{article}
\usepackage[margin=0.25in]{geometry}
\usepackage{pgfplots}
\pgfplotsset{width=10cm,compat=1.9}
% We will externalize the figures
\usepgfplotslibrary{external}
\tikzexternalize
\begin{document}
\begin{tikzpicture}
\begin{axis}[
    axis lines = left,
    xlabel = (x),
    ylabel = {(f(x))},
]
%Below the red parabola is defined
\addplot [
    domain=-10:10,
    samples=100,
    color=red,
]
{x^2 - 2x - 1};
\addlegendentry{(x^2 - 2x - 1)}
%Here the blue parabola is defined
\addplot [
    domain=-10:10,
    samples=100,
    color=blue,
    ]
    {x^2 + 2x + 1};
\addlegendentry{(x^2 + 2x + 1)}
\end{axis}
\end{tikzpicture}
\end{document}

I use xelatex to compile:

xelatex ./demo.tex

But tikz gives me this error message:

(/usr/share/texmf-dist/tex/latex/base/ts1cmr.fd)
*geometry* driver: auto-detecting
*geometry* detected driver: xetex
Package pgfplots notification 'compat/show suggested version=true': you might b
enefit from \pgfplotsset{compat=1.18} (current compat level: 1.9).
===== 'mode=convert with system call': Invoking 'xelatex -halt-on-error -intera
ction=batchmode -jobname "demo-figure0" "\def\tikzexternalrealjob{demo}\input{d
emo}"' ========
! Package tikz Error: Sorry, the system call 'xelatex -halt-on-error -interacti
on=batchmode -jobname "demo-figure0" "\def\tikzexternalrealjob{demo}\input{demo
}"' did NOT result in a usable output file 'demo-figure0' (expected one of .pdf
:.jpg:.jpeg:.png:.bmp:). Please verify that you have enabled system calls. For 
pdflatex, this is 'pdflatex -shell-escape'. Sometimes it is also named 'write 1
8' or something like that. Or maybe the command simply failed? Error messages c
an be found in 'demo-figure0.log'. If you continue now, I'll try to typeset the
 picture.
See the tikz package documentation for explanation.
Type  H <return>  for immediate help.
 ...
l.36 \end{tikzpicture}

why is that? How can I handle it?

Why do you need the line \tikzexternalize?
Everything works without it. — kabenyuk, Mar 27 '22 at 16:38

score 0 · Accepted Answer · answered Mar 27 '22 at 17:10

If all you want to do is generate a plot in your document, remove the lines:

\usepgfplotslibrary{external}
\tikzexternalize

If you want to externalize tikz drawings you need to do shell escape. If you don't know what that means just remove \tikzexternalize and your document will work (although it'll compile slightly slower).

If you want to enable shell escape see How can I enable shell-escape?

How can I use pgfplots to generate a 2D coordinate system image

1 Answers1