[pstricks] shading area under a curve

[Herbert Voss]

Derek Collis schrieb:
> This is good, now can I ask one more question: How can I graph say, 
> y=log x, and shade the region between x=3 and x=4, but without 
> evaluating log 3 and log 4 to give the y-coordinates of the lines x=3 
> and x=4. Is there a way to graph the boundary lines of the shaded region 
> from (3,0) to (3, the point on log x) and (4,0) to (4, the point on log x).
>   


use \SpecialCoor

\documentclass{article}
\usepackage{pst-plot}
\SpecialCoor

\pagestyle{empty}
\begin{document}

\psset{yunit=2}
\begin{pspicture}(-.5,-2)(5,1)
    \psplot[linewidth=1pt,linecolor=blue]{0.01}{5}{x log}
    \pscustom[fillstyle=solid,fillcolor=cyan,linestyle=none]{%
      \psline(3,0)(!3 dup log)
      \psplot{3}{4}{x log}
      \psline(!4 dup log)(4,0)}
    \psaxes{->}(0,0)(-.5,-2)(5,1)
\end{pspicture}

\end{document}


Herbert