[pstricks] Normal arrows along a curve

[Michael Sharpe]

On Aug 8, 2010, at 7:56 PM, Michael Sharpe wrote:

> 
> \usepackage{mathptmx}
> \begin{document}
> %for scaling, use \psset{unit=...}
> \begin{pspicture}(0,0)(4,4)
>   \psparametricplot*[plotpoints=100,linecolor=black!20]{0}{360}{t cos 1 add 1.5 mul t sin 1 add 1.5 mul}
>   \psparametricplot[plotpoints=100]{90}{270}{t cos 1 add 1.5 mul t sin 1 add 1.5 mul}
>   \pscurvepoints[plotpoints=100]{270}{450}{t cos 1 add 1.5 mul t sin 1 add 1.5 mul}{P}%
>   \pspolylineticks[Os=0,Ds=0.2142,ticksize=0 0]{P}%.2142=4.712/23 (4.712=metric range, from log)
>   { ds }{0}{23}% distance
>   \multido{\i=1+1}{22}{\psrline[arrows=->,arrowscale=1.0,linewidth=.4pt](PTick\i)(-7pt;{(PNormal\i)})}%
> \rput(0.1,2.8){$\partial{\Omega}_D$}
> \rput(3.0,-0.05){$\partial{\Omega}_N$}
> \rput(1.6,1.5){$\Omega$}
> \end{pspicture}
> 

A small correction to what I just posted. With the value I proposed for Ds, there are not enough indices. The value has to be reduced slightly. Two of the line should be

   \pspolylineticks[Os=0,Ds=0.214,ticksize=0 0]{P}%.2142=4.712/23 (4.712=metric range, from log)
   { ds }{0}{23}% distance
   \multido{\i=1+1}{21}{\psrline[arrows=->,arrowscale=1.0,linewidth=.4pt](PTick\i)

Michael