CGAL users discussion list

[Alejandro Aragon <>]

Thanks for replying, I actually read the FAQ before posting my message  
and I understand that the double type is inexact. However, I don't see  
why the need of using an "exact" number type when algorithms can be  
modified such that they give exact results within tolerance. If a  
double precision type is exact up to the 15th digit, then algorithms  
should take that into account so when I try to intersect that point  
with the line, the point is supposed to lie over the line within let's  
say tol = 10e-14.

Why would I use an exact number type? I don't want to do that, it will  
slow down a program that I'm actually trying to speed up by doing some  
profiling.

Alejandro M. Aragón

On Jul 23, 2008, at 10:42 AM, Olivier Devillers wrote:

> Alejandro Aragon a écrit :
> > typedef CGAL::Cartesian<double> KernelType;
>
> If you compute with double, rounding errors make your points non  
> collinear
> (e.g. during the decimal to binary conversion if your input is given  
> by
> floating point number in decimal notation)
>
> http://www.cgal.org/FAQ.html#inexact_NT
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