CGAL users discussion list

[Thomas Holzmann <>]

On 03/03/2017 12:50 PM, Laurent Rineau (CGAL/GeometryFactory) wrote:
> Le Friday, March 3, 2017 11:30:48 AM CET Thomas Holzmann a écrit :
> > Hi,
> >
> > I'm using  the epek kernel (without sqrt).
> >
> > I'm having two Vector_3 and want to compute the angle between them.
> >
> > I would usually compute the dot product between the normalized vectors,
> > but I cannot compute the normalized vectors without sqrt.
> >
> > Is there also an (exact) way to compute the angle between the two
> > vectors in CGAL?
> There is no way to compute exact angles. As far as I know, the acos, asin,
> atan, atan2 trigonometric functions are always using floating point numbers.

Ok, thanks for the answer.

Is there a way to normalize exact vectors (without sqrt). When I could 
compute an exact unit vector, the inexact angle computation would not be 
a problem...

Thomas

--
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Dipl.-Ing. Thomas Holzmann
TU Graz - Institut fuer Maschinelles Sehen und Darstellen
Graz University of Technology - Institute for Computer Graphics & Vision
Inffeldgasse 16/II, 8010 Graz, Austria

http://www.icg.tugraz.at/
phone: +43 316 873 5091
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