# [pstricks] PSTricks Digest, Vol 90, Issue 48

James OtterzStuff at Bellsouth.net
Fri Jul 30 17:16:36 CEST 2010

>> Date: Tue, 27 Jul 2010 09:44:05 -0500
>> From: James<OtterzStuff at Bellsouth.net>
>> To: pstricks at tug.org
>> Subject: [pstricks] Normal arrows along a curve
>> Message-ID:<4C4EF0B5.1060307 at Bellsouth.net>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Hi,
>>
>> I am new to PS Tricks, I am trying to draw a (pretty) Neumann boundary
>> condition for a problem. What I need is the ability to place outward
>> normal vectors along a path. So given a curve, you could draw it with a
>> solid line or a dotted line - what I would like is to draw the line
>> solid, but in the places where it would have been dotted, to have an
>> small outward line with arrow. (or just a slightly smaller point size line)
>>
>> How difficult is this? I bring up the similarity to a dotted line,
>> because if it could be implemented at the "line" level, then you could
>> easily draw lines with outward normal arrows using bezier curves, or
>> really anything.
>>
>> Thanks for any help,
>>
>> James

> Check out the section "Ticks and other marks along a curve" in the newest pstricks-add. With any curve, by defining a metric along the curve (eg, arc-length), you can arrange to draw any kind of mark, at intervals governed by that metric. The tangent and normal vectors are defined at each point so that would appear to give you what you need.
>
> Michael
>

Thanks Michael,

That looks a little more complicated than I was hoping.

I initially tried this:

\begin{pspicture}(0,-1.2978102)(6.1428127,1.2978102)
\rput{-90.0}(3.049531,3.049531){\psbezier[linestyle=symbol,symbol=213,symbolFont=ZapfDingbats,startAngle=0,rotateSymbol=true,symbolStep=10pt,symbolWidth=8pt](0,0)(0,4)(6,4)(6,0)}
\end{pspicture}

Where the symbol I wanted to draw with is the "perp" \perp symbol.

The above code does not work, and I am not sure why, I tried several
variations with the font name and the symbol number, but nothing.
I lifted the idea from the PSTricks News 2010, (pst-news10.pdf), page 8.

Assuming I could draw with the symbols, I may be able to draw the figure
twice, once with a dotted line, and again with outward facing pipes or
arrow symbols to get the effect - but I had no luck.

If I get more time, I would like to look into what you referred too.