How to plot atan(x), sqrt(x) using PSTricks?

Question

For example, this code works:

\documentclass{minimal}

\usepackage{pstricks}
\usepackage{pst-plot}

\begin{document}

\begin{pspicture}(-5,-5)(5,5)
  \psgrid[griddots=10,gridlabels=0pt, subgriddiv=0, gridcolor=black!20]
  \psaxes(0,0)(-5,-5)(5,5)
  \psplot[algebraic,xunit=0.5cm,linewidth=1pt]{-5}{5}{x*cos(x)}
\end{pspicture}

\end{document}

But putting atan(x), sqrt(x) (this list is not full I guess) instead of x*cos(x) gives me nothing at all.

Answer 1

The pst-math package provides the ATAN function for the inverse tangent function. The sqrt function has domain [0,\infty) which is why your code didn't work (you were supplying it with a domain of [-5,5])

\documentclass{article}

\usepackage{pst-plot}
\usepackage{pst-math}

\begin{document}

\psset{algebraic,unit=0.5cm,linewidth=1pt}

\begin{pspicture}(-5,-5)(5,5)
  \psgrid[griddots=10,gridlabels=0pt, subgriddiv=0, gridcolor=black!20]
  \psaxes(0,0)(-5,-5)(5,5)
  \psplot{0}{5}{sqrt(x)}
  \psplot[linecolor=red]{-5}{5}{ATAN(x)}
\end{pspicture}

\end{document}

Answer 2

it is also possible to draw the root function as a parametric plot, then you do not have to take care of negative values:

\documentclass{article}
\usepackage{pst-plot}
\usepackage{pst-math}
\begin{document}

\begin{pspicture}(-5,-3)(5,3)
  \psgrid[griddots=10,gridlabels=0pt, subgriddiv=0, gridcolor=black!40]
  \psaxes[axesstyle=frame,Dx=2,Dy=2](0,0)(-5,-3)(5,3)
  \psset{algebraic,linewidth=1.5pt}
  \psparametricplot{-2.2}{2.2}{t^2 | t}
  \psplot[linecolor=red]{-5}{5}{ATAN(x)}
\end{pspicture}

\end{document}

Answer 3

\documentclass[pstricks,border={0pt -5mm 0pt -1mm}]{standalone}
\usepackage{pst-plot,pst-math}
\usepackage[nomessages]{fp}
\FPeval\PiQ{round(pi/4:3)}

\psset{algebraic,plotpoints=100}



\newpsstyle{gridstyle}
{
    gridwidth=0.4pt,% 0.8pt
    gridcolor=red!30,% black
    griddots=0,% 0 
    %=====================================
    gridlabels=0pt,% 10pt
    gridfont=NimbusSanL-Regu,
    gridlabelcolor=blue!50,% black, must not use dvipsnames
    %=====================================
    subgriddiv=5,% 5
    subgridwidth=0.2pt,% 0.4pt
    subgridcolor=green!30,% gray
    subgriddots=0,% 0
}

\begin{document}

\begin{pspicture*}[showgrid=bottom](-5.2,-\psPi)(5.7,\psPi)
  \psplot[linecolor=blue]{0}{5}{sqrt(x)}
  \psplot[linecolor=red]{-5}{5}{ATAN(x)}
    \psaxes
    [
        ytrigLabels=true,
        linewidth=\pslinewidth,
        labelFontSize=\scriptscriptstyle,
        tickcolor=gray,
        ticksize=-1.5pt 1.5pt,
        xlabelsep=3pt,
        arrowscale=1,
        trigLabelBase=4,        
        dy=\PiQ,% must come before yunit to avoid getting a strange output!
        yunit=\PiQ, 
    ]{->}(0,0)(-5.1,-\psPi)(5.3,\psPi)[$x$,0][$y$,90]
\end{pspicture*}

\end{document}

Answer 4

And because we're always encouraged to do things differently, here's a version that uses pgfplots. Note that this package uses degrees by default, so we need to convert to radians.

\documentclass{article}
\usepackage{pgfplots}

\pgfplotsset{every axis/.append style={
                    axis x line=middle,    % put the x axis in the middle
                    axis y line=middle,    % put the y axis in the middle
                    axis line style={<->}, % arrows on the axis
                    xlabel={$x$},          % default put x on x-axis
                    ylabel={$y$},          % default put y on y-axis
                }}

\begin{document}

\begin{tikzpicture}
    \begin{axis}[xmin=-5,xmax=5,
                             ymin=-5,ymax=5,
                             grid=both]
            \addplot[red]expression[domain=0:5]{sqrt(x)};
            \addplot[blue]expression[domain=-5:5]{rad(atan(x))};
    \end{axis}
\end{tikzpicture}

\end{document}