[R] Slope of surface

[Clint Bowman]

If I recall my computer graphics (decades ago at Utah), doesn't the cross 
product enter in here?  I'm hoping someone with more recent experience 
will have fewer cobwebs overlaying the knowledge here.

Clint

On Tue, 19 Oct 2004, Uwe Ligges wrote:

> Laura Quinn wrote:
> 
> > Hi,
> > 
> > Is there a neat way of working out the slope of a flat surface in R?
> > Given (x,y,z) co-ordinates of the four corners of a square, 
> 
> three should be sufficient
> 
> 
>  > s there a
> > function which will allow me to calculate the "mean" slope of the surface
> > in a given direction?
> 
> Along the axis, one way without any thinking is to apply a regression 
> with e=0, the neater way is to calculate the true result simply. Just 
> insert one formula into the other ...
> 
> Uwe Ligges
> 
> 
> > Thanks in advance..
> > 
> > Laura
> > 
> > Laura Quinn
> > Institute of Atmospheric Science
> > School of Earth and Environment
> > University of Leeds
> > Leeds
> > LS2 9JT
> > 
> > tel: +44 113 343 1596
> > fax: +44 113 343 6716
> > mail: laura at env.leeds.ac.uk
> > 
> > ______________________________________________
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> 
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Clint Bowman			INTERNET:	clint at ecy.wa.gov
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