Yes.
Thank you very much.
I have just started coding with C++ in several month and this is really
helpful for me.
Best,
Kien
Vào Th 6, 22 thg 2, 2019 vào lúc 21:15 Jean-Paul Pelteret <
jppelte...@gmail.com> đã viết:
> Dear Kien,
>
> The problem that you’re facing (in the example that you gave us) is not
> one to do with deal.II itself, but rather C++ and how you’ve structured
> your code. When I build your code in debug mode, I see this warning:
>
> $ make
> Scanning dependencies of target problem
> [ 50%] Building CXX object CMakeFiles/problem.dir/problem.cc.o
> <path>/problem.cc:112:31: warning: field 'order' is uninitialized when
> used here [-Wuninitialized]
> fe(FE_NedelecSZ<dim>(order), 1, //(order), multiplicity
>
> and when I run it, it actually hangs on my machine. What’s happening here
> relates to where you have this line:
>
> const unsigned int order = 3;
>
> It is in the body of the EM class, but most critically its below the
> declarations for
>
> DoFHandler<dim> dof_handler;
> FESystem<dim> fe;
>
> This means that the “order” variable is initialised AFTER the
> “dof_handler", and “fe”, and so during the call to the constructor it
> uninitialised when used to initialise the “dof_handler” and “fe”. So why
> this hangs on my machine is likely because “order” is random number, and
> more specifically something very large when I tested it. Its luck that it
> the section of memory assigned to this variable was either all zeros (with
> the interpretation of the uninitialised “order” variable being equal to
> zero, which corresponds to the lowest order Nedelec element that is
> permitted) or with some random bits that were interpreted as a small number.
>
> The quick fix to the issue is to move the definition of “order” above that
> of “dof_handler”. Then the warning goes away and everything works as
> expected. If I change the constructor definition slightly to
>
> template<int dim>
> EM<dim>::EM()
> :dof_handler(triangulation),
> fe(FE_NedelecSZ<dim>(order), 1, //(order), multiplicity
> FE_NedelecSZ<dim>(order), 1)
> {
> std::cout << "order: " << order << " fe.dofs_per_cell: " <<
> fe.dofs_per_cell << std::endl;
> }
>
> then I get the following output for two different orders.:
> order: 2 fe.dofs_per_cell: 288
> order: 3 fe.dofs_per_cell: 600
>
> A better fix might be to pass the order into the constructor, or to use a
> parameter handler to choose the order at run-time.
>
> I hope that this helps you understand where things were going wrong.
>
> Best,
> Jean-Paul
>
> On 22 Feb 2019, at 02:37, Phạm Ngọc Kiên <ngockien.lea...@gmail.com>
> wrote:
>
> Hi,
> The attachment is my small program that I created.
> My fe system have 24 dofs for both real and imaginary of 12 edges of a
> cell.
> No matter how I change the parameter "order" the number of dofs is
> unchanged.
> I think I have problem when constructing the object.
> I would like to thank you very much.
> Best,
> Kien
>
> Vào Th 5, 21 thg 2, 2019 vào lúc 23:38 Wolfgang Bangerth <
> bange...@colostate.edu> đã viết:
>
>> On 2/20/19 7:01 PM, Phạm Ngọc Kiên wrote:
>> > I tested in my codes using
>> >
>> > template<int dim>
>> > CSEM<dim>::CSEM()
>> > ://mapping(1),
>> > dof_handler(triangulation),
>> > fe(FE_NedelecSZ<dim>(order),1,//(order), multiplicity
>> > FE_NedelecSZ<dim>(order),1) {}
>> >
>> > When I changed the parameter order, I saw only the number of dofs was
>> only of lowest order dofs no matter how big the order was
>> >
>> > I think that there should be a way to get higher order dofs, but I
>> cannot find it now.
>>
>> Can you create a small program that demonstrates this issue?
>>
>> Best
>> W.
>>
>> --
>> ------------------------------------------------------------------------
>> Wolfgang Bangerth email: bange...@colostate.edu
>> www: http://www.math.colostate.edu/~bangerth/
>>
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