Draw a curve in latex using PSTricks

Question

I would like to draw a curve in latex but when I put this code

\psset{algebraic=true}
\pspicture(-2,-0.5)(2,2)

\psline{<->}(-2,0)(2,0)
\psline{->}(0,-0.5)(0,2)
\psplot{-1.5}{1}{x*x+x}

\endpspicture

theses errors appear

! Undefined control sequence.<recently read> \c@lor@to@ps \psline(
! Undefined control sequence.\XC@usec@lor ...string \color@ #1#2\endcsname \@@\fi \space \psline(
! Undefined control sequence.<recently read> \c@lor@to@ps \psline

Please if someone can help me because i didn't understand why this error appears.

\documentclass{article}
\usepackage[french]{babel} 
\usepackage{color} 
\usepackage{xcolor} %les couleurs 
\definecolor{myblue}{rgb}{0.2,0.4,1} 
\usepackage{layout} 
\usepackage[top=2 cm, bottom=2 cm, left=2 cm, right=2 cm]{geometry} 
\usepackage{setspace} 
\usepackage{graphicx} 
\usepackage{array} 
\usepackage{pstricks-add} 
\usepackage{pst-eucl} 

\begin{document} 
\psset{algebraic=true} 
\pspicture(-2,-0.5)(2,2) 
\psline{<->}(-2,0)(2,0) 
\psline{->}(0,-0.5)(0,2) 
\psplot{-1.5}{1}{x*x+x} 
\endpspicture 
\end{document} 

Answer 1

The main problem with your MWE was the line

\usepackage[pdftex]{graphicx}

which, when using PSTricks will cause some problems (unless you use How to use PSTricks in pdfLaTeX?)

Note also that there's no need to load the color AND xcolor package- only load the xcolor package in the future.

I've stripped your code down to the following, which works either with xelatex or with the latex->dvips->ps2pdf routine.

\documentclass{article}
\usepackage[french]{babel} 
\usepackage{pstricks-add} 

\begin{document} 
\psset{algebraic=true} 
\pspicture(-2,-0.5)(2,2) 
\psline{<->}(-2,0)(2,0) 
\psline{->}(0,-0.5)(0,2) 
\psplot{-1.5}{1}{x*x+x} 
\endpspicture 
\end{document} 

Answer 2

When using PStricks with PDF output, you need to either

1. Compile with latex and then run dvi2pdf.
2. Compile with xelatex.
3. Compile with pdflatex with \usepackage{auto-pst-pdf}.

In the first two cases, you need to remove the pdftex option from \usepackage{graphicx}, and in the third case, it is still recommended to omit the option.

Alternatively, you could

1. Use pgfplots, which works natively with pdflatex. For example

\documentclass{article}
\usepackage{pgfplots}

\begin{document}
\begin{tikzpicture}
\begin{axis}[axis lines=middle, enlargelimits=true, xtick=\empty, ytick=\empty]
\addplot [domain=-1.5:1, thick] {x^2+x};
\end{axis}
\end{tikzpicture}
\end{document}

will give you

Answer 3

Plotting a curve to which you supply your own data points using pstricks is possible using pst-plot. You can either input the data directly in your .tex file, or read it from an external file. Here's a small example, taken from the pst-plot documentation (see section 2 Plotting data records, p 5-6):

\documentclass{article}
\usepackage{pst-plot}% http://ctan.org/pkg/pst-plot
\usepackage{filecontents}% http://ctan.org/pkg/filecontents
\begin{document}
\begin{pspicture}(4,3)
  \psset{xunit=.2cm,yunit=1.5cm}
  \savedata{\mydata}[
    {{0, 0}, {1., 0.946083}, {2., 1.60541}, {3., 1.84865}, {4., 1.7582},
    {5., 1.54993}, {6., 1.42469}, {7., 1.4546}, {8., 1.57419},
    {9., 1.66504}, {10., 1.65835}, {11., 1.57831}, {12., 1.50497},
    {13., 1.49936}, {14., 1.55621}, {15., 1.61819}, {16., 1.6313},
    {17., 1.59014}, {18., 1.53661}, {19., 1.51863}, {20., 1.54824}}]
  \dataplot[plotstyle=curve,showpoints,dotstyle=triangle]{\mydata}
  \psline{<->}(0,2)(0,0)(22,0)
\end{pspicture}

\bigskip

\begin{filecontents*}{foo.data}
[{0, 0}, {1., 0.946083}, {2., 1.60541}, {3., 1.84865}, {4., 1.7582},
 {5., 1.54993}, {6., 1.42469}, {7., 1.4546}, {8., 1.57419},
 {9., 1.66504}, {10., 1.65835}, {11., 1.57831}, {12., 1.50497},
 {13., 1.49936}, {14., 1.55621}, {15., 1.61819}, {16., 1.6313},
 {17., 1.59014}, {18., 1.53661}, {19., 1.51863}, {20., 1.54824}]
\end{filecontents*}

\begin{pspicture}(4,3)
  \psset{xunit=.2cm,yunit=1.5cm}
  \readdata{\foo}{foo.data}
  \dataplot[plotstyle=curve,showpoints,dotstyle=diamond]{\foo}
  \psline{<->}(0,2)(0,0)(22,0)
\end{pspicture}

\end{document}​

Answer 4

Compile with pdflatex --shell-escape filename.tex or xelatex --shell-escape filename.tex.

%filename.tex
\documentclass{article}

\usepackage{filecontents}

\begin{filecontents*}{xxx.tex}
\documentclass[pstricks,border=0pt]{standalone}
\usepackage{pstricks-add} 
\begin{document} 
\pspicture*[showgrid](-2,-1)(2,2) 
    \psaxes{->}(0,0)(-1.75,-0.75)(1.5,1.5)[$x$,0][$y$,90]
    \psplot[algebraic,linecolor=red]{-1.5}{1}{x^2+x} 
\endpspicture* 
\end{document} 
\end{filecontents*}


\usepackage{graphicx}

\def\fig#1#2{
    \immediate\write18{xelatex #1}%
    \begin{figure}
        \centering
        \includegraphics[width=0.5\linewidth]{#1}
        \caption{#2}
        \label{fig:#1}
    \end{figure}%
}
\begin{document}
    \fig{xxx}{This is the graph of $y=f(x)=x^2+x$}
\end{document}