CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Hi Noel,

Could you try with CGAL::Simple_cartesian<CGAL::Gmpq> ?

The stream operator with EPEC kernel is using to_double on the 
coordinates IIRC.

Sebastien.

On 11/19/2012 09:50 AM, Noel Warren wrote:
> I'm using the Exact_predicates_exact_constructions kernel to construct
> my Nef polyhedra and I believe I've run into a bug.  The Nef seems to
> have no problem being stringified.  When I try to rebuild the nef with
> the string it will often fail.
>
> I try a simple tetrahedron with points (0,0,0)(1,0,0)(0,1,0)(0,0,1) and
> everything works fine.  But if I change the last point to have a value
> of (0,0,1.1) it fails.  You might think that the problem has something
> to do with floats, but it doesn't.  1.5 works fine as does 0.75
>
> As you probably know, the points are represented as a quotient with both
> the numerator and denominator being integers.  The problem seems to be
> that when these integers (gmpz) are being output with the << operator
> they get abbreviated when too long (eg: 2.47698e+15).  This not only
> leads to a loss in precision but means the file can not be read, as gmpz
> cannot parse the integer in that format.  Here is my failing tetrahedron
> example (see fourth point) ...
>
> Selective Nef Complex
> standard
> vertices   4
> halfedges  12
> facets     8
> volumes    2
> shalfedges 24
> shalfloops 0
> sfaces     8
> 0 { 0 2, 0 5, 0 1, -2 | 0 0 0 1 } 1
> 1 { 3 5, 6 11, 2 3, -2 | 1 0 0 1 } 1
> 2 { 6 8, 12 17, 4 5, -2 | 0 1 0 1 } 1
> 3 { 9 11, 18 23, 6 7, -2 | 0 0 2.47698e+15 2.2518e+15 } 1
> 0 { 4, 0, 0 0 | 1 0 0 1 } 1
> 1 { 6, 0, 0 1 | 0 1 0 1 } 1
> 2 { 9, 0, 0 3 | 0 0 1 1 } 1
> 3 { 7, 1, 0 6 | -1 1 0 1 } 1
> 4 { 0, 1, 0 7 | -1 0 0 1 } 1
> 5 { 11, 1, 0 9 | -2.2518e+15 0 2.47698e+15 1 } 1
> 6 { 1, 2, 0 12 | 0 -1 0 1 } 1
> 7 { 3, 2, 0 13 | 1 -1 0 1 } 1
> 8 { 10, 2, 0 15 | 0 -2.2518e+15 2.47698e+15 1 } 1
> 9 { 2, 3, 0 18 | 0 0 -1 1 } 1
> 10 { 8, 3, 0 19 | 0 2.2518e+15 -2.47698e+15 1 } 1
> 11 { 5, 3, 0 21 | 2.2518e+15 0 -2.47698e+15 1 } 1
> 0 { 1, 4 , , 0 | 0 -1 0 0 } 1
> 1 { 0, 5 , , 1 | 0 1 0 0 } 1
> 2 { 3, 20 , , 0 | 2.47698e+15 2.47698e+15 2.2518e+15 -2.47698e+15 } 1
> 3 { 2, 21 , , 1 | -2.47698e+15 -2.47698e+15 -2.2518e+15 2.47698e+15 } 1
> 4 { 5, 2 , , 0 | -1 0 0 0 } 1
> 5 { 4, 3 , , 1 | 1 0 0 0 } 1
> 6 { 7, 0 , , 0 | 0 0 -1 0 } 1
> 7 { 6, 1 , , 1 | 0 0 1 0 } 1
> 0 { 0 } 0
> 1 { 1 } 1
> 0 { 1, 4, 2, 0, 1, 6, 12, 6 | 0 0 1 0 } 1
> 1 { 0, 3, 5, 1, 0, 13, 7, 7 | 0 0 -1 0 } 1
> 2 { 3, 0, 4, 1, 1, 16, 18, 4 | 1 0 0 0 } 1
> 3 { 2, 5, 1, 2, 0, 19, 17, 5 | -1 0 0 0 } 1
> 4 { 5, 2, 0, 2, 1, 22, 8, 0 | 0 1 0 0 } 1
> 5 { 4, 1, 3, 0, 0, 9, 23, 1 | 0 -1 0 0 } 1
> 6 { 7, 10, 8, 3, 3, 12, 0, 6 | 0 0 1 0 } 1
> 7 { 6, 9, 11, 4, 2, 1, 13, 7 | 0 0 -1 0 } 1
> 8 { 9, 6, 10, 4, 3, 4, 22, 0 | 0 1 0 0 } 1
> 9 { 8, 11, 7, 5, 2, 23, 5, 1 | 0 -1 0 0 } 1
> 10 { 11, 8, 6, 5, 3, 20, 14, 2 | -2.47698e+15 -2.47698e+15 -2.2518e+15 0 } 1
> 11 { 10, 7, 9, 3, 2, 15, 21, 3 | 2.47698e+15 2.47698e+15 2.2518e+15 0 } 1
> 12 { 13, 16, 14, 6, 5, 0, 6, 6 | 0 0 1 0 } 1
> 13 { 12, 15, 17, 7, 4, 7, 1, 7 | 0 0 -1 0 } 1
> 14 { 15, 12, 16, 7, 5, 10, 20, 2 | -2.47698e+15 -2.47698e+15 -2.2518e+15
> 0 } 1
> 15 { 14, 17, 13, 8, 4, 21, 11, 3 | 2.47698e+15 2.47698e+15 2.2518e+15 0 } 1
> 16 { 17, 14, 12, 8, 5, 18, 2, 4 | 1 0 0 0 } 1
> 17 { 16, 13, 15, 6, 4, 3, 19, 5 | -1 0 0 0 } 1
> 18 { 19, 22, 20, 9, 7, 2, 16, 4 | 1 0 0 0 } 1
> 19 { 18, 21, 23, 10, 6, 17, 3, 5 | -1 0 0 0 } 1
> 20 { 21, 18, 22, 10, 7, 14, 10, 2 | -2.47698e+15 -2.47698e+15
> -2.2518e+15 0 } 1
> 21 { 20, 23, 19, 11, 6, 11, 15, 3 | 2.47698e+15 2.47698e+15 2.2518e+15 0 } 1
> 22 { 23, 20, 18, 11, 7, 8, 4, 0 | 0 1 0 0 } 1
> 23 { 22, 19, 21, 9, 6, 5, 9, 1 | 0 -1 0 0 } 1
> 0 { 0, 1 , , , 0 } 0
> 1 { 0, 0 , , , 1 } 1
> 2 { 1, 7 , , , 0 } 0
> 3 { 1, 6 , , , 1 } 1
> 4 { 2, 13 , , , 0 } 0
> 5 { 2, 12 , , , 1 } 1
> 6 { 3, 19 , , , 0 } 0
> 7 { 3, 18 , , , 1 } 1
> /* end Selective Nef complex */