Skip to Content.
Sympa Menu

cgal-discuss - Re: [cgal-discuss] Difference between Lazy_exact and Filtered_kernel?

Subject: CGAL users discussion list

List archive

Re: [cgal-discuss] Difference between Lazy_exact and Filtered_kernel?


Chronological Thread 
  • From: Andreas Fabri <>
  • To:
  • Subject: Re: [cgal-discuss] Difference between Lazy_exact and Filtered_kernel?
  • Date: Thu, 03 Jul 2008 18:44:09 +0200

Thomas Zangl - Home wrote:
Am Thu, 03 Jul 2008 15:21:43 +0200, schrieb "Andreas Fabri" <>:

Hi!

Another question which arise during testing:

in ftp://ftp-sop.inria.fr/geometrica/pion/publis/lazy-kernel.pdf you
make a comparison between different kernels. Now, I ask myself:

if I use:
typedef CGAL::Simple_cartesian<CGAL::Gmpq> K;
typedef CGAL::Gmpq dbl;

all predicates and operations are done exactly? Like if the
filter of the Filtered_Kernel always returns "NO_IDEA"?
The reason is, if I use the plain Exact_pred_exact_constr. kernel, my
test app does not produce any degenerate cases. If I use the kernel
typedef'd above, I get a lot of them. It seems, computation accuracy is
far worse with the Simple_cartesian<CGAL::Gmpq> in my case.

Can you give a minimalistic code example.

andreas

Any idea why this can happen? How can I clarify that all computations
are done using exact arithmetic like described in your paper?
TIA,




Archive powered by MHonArc 2.6.16.

Top of Page