[pstricks] tangential vector

[Michael Sharpe]

On Apr 8, 2009, at 8:45 AM, Doris Wagner wrote:

> hi list,
>
> I have a graph which shows a trajectory (e.g. polynomial) of a
> physical object and I want to draw the tangent vector. the problem
> with \psplotTangent is that it goes in two directions from one point
> of the graph. is there a possibility to get only half of it?
>
> d

I don't know if this is possible with \psplotTangent, but you can  
accomplish the same thing another way. I wrote a package pst- 
nodeExtras with an example showing how do do this. Take a look at the  
documentation, looking for \psxline and \curvepnode.

http://math.ucsd.edu/~msharpe/pst-nodeExtras-doc.pdf

To use, download and place in a location searched by TeX

http://math.ucsd.edu/~msharpe/pst-nodeExtras.tex
http://math.ucsd.edu/~msharpe/pst-nodeExtras.sty

Then \usepackage{pst-nodeExtras}

Michael