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[Edoardo Milotti <>]

Dear Sylvain , thank very much you for you answer, however I have one further question. 

I insert points in the triangulation as follows (to maintain the original order I use a sequential insertion)

for(vector<Point>::iterator it=v.begin(); it!=v.end(); it++)

T.insert(*it);

I add vertex info

for (Finite_vertices_iterator vit = T.finite_vertices_begin(); vit != T.finite_vertices_end(); ++vit)

{

vit->info() = k;

k++;

}

then I use the named vertices in a further loop 

for (Finite_vertices_iterator vit = T.finite_vertices_begin(); vit != T.finite_vertices_end(); ++vit)

{

T.incident_vertices(vit, back_inserter(vn)); // list of named neighbors ...

... etc ... 

The order of the list of finite incident vertices in the last loop turns out different at some point, like this 

first run

- 8 1.93693532e-11 9.08382265e-06 2.132290991e-06

- 5 3.478538238e-11 8.274341753e-06 4.204006e-06

- 10 1.273731276e-11 9.54219939e-06 1.334840348e-06

- 6 1.795678855e-11 9.23188419e-06 1.945083818e-06

- 9 2.62181266e-11 8.721762172e-06 3.006058419e-06

- 1 4.740207202e-12 1.002035364e-05 4.730578752e-07

- 0 7.036177754e-11 3.051055408e-06 2.306145518e-05

second run 

- 8 1.93693532e-11 9.08382265e-06 2.132290991e-06

- 10 1.273731276e-11 9.54219939e-06 1.334840348e-06

- 5 3.478538238e-11 8.274341753e-06 4.204006e-06

- 6 1.795678855e-11 9.23188419e-06 1.945083818e-06

- 9 2.62181266e-11 8.721762172e-06 3.006058419e-06

- 0 7.036177754e-11 3.051055408e-06 2.306145518e-05

- 1 4.740207202e-12 1.002035364e-05 4.730578752e-07

here the first column is the vertex name, while the other three columns contain geometric information, and in particular the second one is the distance between the finite vertex under consideration and on of its finite incident vertices. The distances are the same, only the order appears to be shuffled. I guessed that this is due to the internal random number generator, however I am no longer so sure now. I use long double's to represent point coordinates (16 bytes): could it be some type conversion and precision problem inside CGAL that determines a different output order? 

Thank you very much, 

Edoardo Milotti

On 23/gen/2010, at 15.02, Sylvain Pion wrote:

Le 23/01/10 10:03, Edoardo Milotti a écrit :

I use Triangulation_hierarchy_3, and I insert vertices one by one in a

fixed order: I noticed that the triangulation output is shuffled and the

order is different every time I run my program. Can anybody please tell

me how to set the seed of the internal random number generator in order

to obtain a reproducible output? Thanks.

By "output order", you meant the Cell_iterator order, not
the Vertex_iterator order, right ?

Does the following patch solve your problem ?

--- Triangulation_3.h (revision 52267)
+++ Triangulation_3.h (working copy)
@@ -207,7 +207,6 @@
  Tds _tds;
  GT  _gt;
  Vertex_handle infinite; //infinite vertex
-  mutable Random rng;
    Comparison_result
  compare_xyz(const Point &p, const Point &q) const
@@ -1501,6 +1500,8 @@
   start = start->neighbor(ind_inf);
    }
+  Random rng (0L);
+
  switch (dimension()) {
  case 3:
    {

--
Sylvain Pion
INRIA Sophia Antipolis
Geometrica Project-Team
CGAL, http://cgal.org/

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