Thank you for quick reply!!!
I tried your suggestions but I couldn't resolve the problem.....
The more weird thing is if I commands as..
GridGenerator::hyper_cube (triangulation, 0, 1);
triangulation.refine_global ();
for (typename Triangulation<dim>::active_cell_iterator
cell=triangulation.begin_active();
cell!=triangulation.end(); ++cell)
{
for (unsigned int f=0; f<GeometryInfo<dim>::faces_per_cell;
++f)
{
if ( std::abs(cell->face(f)->center()[0]-0.5)< 1e-12 )
{
cell->face(f)->set_all_boundary_ids(1);
}
}
}
<https://lh3.googleusercontent.com/-vxXjt_6106w/WCjEWZXkl9I/AAAAAAAAA9M/HtP_S_FZR3wqpaBSHpe7SjgNG9tCnYX5gCLcB/s1600/Screen%2BShot%2B2016-11-13%2Bat%2B1.50.56%2BPM.png>
2016년 11월 13일 일요일 오후 1시 35분 3초 UTC-6, Jean-Paul Pelteret 님의 말:
>
> Hi Jaekwang,
>
> With what you've shown I'm going to guess that your problem might simply
> be related to numerical / round-off error associated with floating point
> calculations.
>
> if ( cell->face(f)->center()[0]==1 ) // The LHS value is a computed
>> double, and the RHS value is an integer which will be cast to a double for
>> comparison
>
>
> Take a look at the mesh-generation part in the introduction to step-2
> <https://www.dealii.org/developer/doxygen/deal.II/step_2.html#Meshgenerationhttps://www.dealii.org/developer/doxygen/deal.II/step_2.html%23Meshgeneration>
> for
> how one best implements these types of comparisons. They're particularly
> relevant when dealing with the geometry, especially in more complex
> scenarios. Admittedly the step-2 example is for a circular geometry but the
> same concept applies:
>
> if ( std::abs(cell->face(f)->center()[0]) < 1e-10 ) ...
>
> if ( std::abs(cell->face(f)->center()[0] - 1.0) < 1e-10 ) ...
>
> You can almost never be certain that any calculated floating point value
> will be an exact match to an implicitly cast integer value right down to
> machine precision, which is what will be checked with the equality operator.
>>
>>
> I hope that this fixes your issue.
>
> Regards,
> J-P
>
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