Greetings everyone, I want to express my gratitude for your assistance with my question, which has evolved into something more profound.
Regarding the function "VectorFucntionFromScalarFunctionObject," I have observed that it works for computing the L2 norm of the error. However, when I attempted to compute the H1_seminorm of the error, I noticed that the gradient was not implemented for this function. Please let me know if my understanding is incorrect, as I referred to the <deal.II/base/function.h> for this. I am curious if there is a way to resolve this issue. My idea is to obtain the gradient of the "FeFeildFunction" since I know that the gradient is implemented for this function, as per <deal.II/numerics/fe_field_function.h>. Afterward, I can define a new function within a class, based on "VectorFucntionFromScalarFunctionObject," where the gradient of that function would be the gradient of the "FeFeildFunction." Could you kindly advise me on the simplest way to accomplish this? On a side note, although "VectorFucntionFromScalarFunctionObject" works with the L2 norm of the error, it is quite computationally intensive. Best regards, Najwa On Sunday, July 23, 2023 at 4:47:50 PM UTC+3 Najwa Alshehri wrote: > Dear Luca, > > This is interesting. I am exited to try this out. > > Thank you so much, > Najwa > > On Sunday, July 23, 2023 at 3:39:05 PM UTC+3 luca....@gmail.com wrote: > >> FEFieldFunction has the same number of components of the underlying >> dofhandler. If that has one component, then so does the FEFieldFunction. >> What you could do is wrap the FEFieldFunction into another function, e.g. >> >> The deal.II Library: VectorFunctionFromScalarFunctionObject< dim, >> RangeNumberType > Class Template Reference >> <https://www.dealii.org/current/doxygen/deal.II/classVectorFunctionFromScalarFunctionObject.html> >> dealii.org >> <https://www.dealii.org/current/doxygen/deal.II/classVectorFunctionFromScalarFunctionObject.html> >> [image: deal.ico] >> <https://www.dealii.org/current/doxygen/deal.II/classVectorFunctionFromScalarFunctionObject.html> >> >> <https://www.dealii.org/current/doxygen/deal.II/classVectorFunctionFromScalarFunctionObject.html> >> >> You could pass a lambda function as an argument to the constructor of the >> function, that uses your FEFieldFunction object, I.e., >> >> VectorFucntionFromScalarFuncObj<dim> my_fun([&](const auto &p){ return >> fe_field_func.value(p);}, 0, 2); >> >> Luca >> >> Il giorno 21 lug 2023, alle ore 22:05, Najwa Alshehri < >> najwaa...@gmail.com> ha scritto: >> >> Dear Daniel, your answer makes sense, Finally it worked. >> >> >> Dear Luca, thank you for your answer. Indeed, the ExactSolution is a >> class I built myself. I followed your suggestion and it was the magic line >> that solved the issue. *However,* say that I have in another code >> instead of using a ExactSolution that I build myself, I used an >> FeFieldFunction for a reference solution, how would I make this function >> allocate two components? >> >> Best, >> Najwa >> >> On Friday, July 21, 2023 at 1:54:42 PM UTC+3 luca....@gmail.com wrote: >> >>> Dear Najwa, >>> >>> how many components do the `ExactSolution2<dim>` function has? >>> >>> The error complains about `exact_solution.n_components, n_components` >>> not being equal, in particular it tells you that `ExactSolution2<dim>` only >>> has one component. >>> >>> If you built the ExactSolution class yourself, make sure at construction >>> time you tell Function<dim> to allocate two components: >>> >>> ExactSolution2<dim>::ExactSolution2<dim>( … ) >>> : Functions::Function<dim>(2) >>> >>> Best, >>> Luca. >>> >>> >>> > On 20 Jul 2023, at 12:15, Najwa Alshehri <najwaa...@gmail.com> wrote: >>> > >>> > Hello again, >>> > >>> > I have a follow-up question. Does this ComponentSelectFunction work >>> also with vectors that are not written as blocked vectors? I have applied >>> it before when I was dealing with blocked vectors and it worked perfectly. >>> > >>> > So, I did this, >>> > const ComponentSelectFunction<dim> primal_mask(0,2); >>> > Later, >>> > VectorTools::integrate_difference(omega2_dh, >>> > u_omega2, >>> > ExactSolution2<dim>(), >>> > cellwise_errors2, >>> > quadrature, >>> > VectorTools::L2_norm >>> > ,&primal_mask); >>> > const double u2_l2_error = >>> > VectorTools::compute_global_error(triangulation_omega2, >>> > cellwise_errors2, >>> > VectorTools::L2_norm); >>> > >>> > And I got the following error!! >>> > An error occurred in line <455> of file >>> <../include/deal.II/numerics/vector_tools_integrate_difference.templates.h> >>> in function >>> > void dealii::VectorTools::internal::do_integrate_difference(const >>> dealii::hp::MappingCollection<dim, spacedim>&, const >>> dealii::DoFHandler<dim, spacedim>&, const InVector&, const >>> dealii::Function<spacedim, typename InVector::value_type>&, OutVector&, >>> const dealii::hp::QCollection<dim>&, const dealii::VectorTools::NormType&, >>> const dealii::Function<spacedim>*, double) [with int dim = 2; int spacedim >>> = 2; InVector = dealii::Vector<double>; OutVector = dealii::Vector<double>; >>> typename InVector::value_type = double] >>> > The violated condition was: >>> > >>> ::dealii::deal_II_exceptions::internals::compare_for_equality(exact_solution.n_components, >>> >>> n_components) >>> > Additional information: >>> > Dimension 1 not equal to 2. >>> > >>> > Obviously, we have dimensionality mismatching between u_omega2 and the >>> exact solution. which means that the mask is not really picking up the >>> first component of the solution u_omega2. Do you have any suggestions to >>> fix this issue? >>> > >>> > Appreciate your help, >>> > Najwa >>> > On Thursday, July 20, 2023 at 11:48:04 AM UTC+3 Najwa Alshehri wrote: >>> > Thank you Daniel for the clear quick answer. I will follow it. >>> > >>> > Best, >>> > Najwa >>> > >>> > On Wednesday, July 19, 2023 at 5:16:14 PM UTC+3 d.arnd...@gmail.com >>> wrote: >>> > Najwa, >>> > >>> > The documentation of VectorTools::integrate_difference( >>> https://www.dealii.org/current/doxygen/deal.II/namespaceVectorTools.html#a676190d2c897ac5da68a9c460fa95832) >>> >>> says >>> > >>> > >>> > The additional argument weight allows to evaluate weighted norms. The >>> weight function may be scalar, establishing a spatially variable weight in >>> the domain for all components equally. This may be used, for instance, to >>> only integrate over parts of the domain. The weight function may also be >>> vector-valued, with as many components as the finite element: Then, >>> different components get different weights. A typical application is when >>> the error with respect to only one or a subset of the solution variables is >>> to be computed, in which case the other components would have weight values >>> equal to zero. The ComponentSelectFunction class is particularly useful for >>> this purpose as it provides such a "mask" weight. The weight function is >>> expected to be positive, but negative values are not filtered. The default >>> value of this function, a null pointer, is interpreted as "no weighting >>> function", i.e., weight=1 in the whole domain for all vector components >>> uniformly. >>> > >>> > Best, >>> > Daniel >>> > >>> > On Wed, Jul 19, 2023 at 8:01 AM Najwa Alshehri <najwaa...@gmail.com> >>> wrote: >>> > Dear group members, >>> > >>> > I have one question, >>> > >>> > I am trying to calculate the L2 norm of the error of a solution. In >>> particular, I have a vector of the solution u_omega and a FeSystem with two >>> fes. >>> > I am interested in computing the L2 norm of the error related to the >>> first fe using integrate_difference function. (Note here u_omega is not a >>> blocked vector, however, it has two solutions stacked together in one >>> vector). Can I extract the solution of the first part from u_omega? >>> > >>> > >>> > Thank you in advance for your help. >>> > Best, >>> > Najwa >>> > >>> > -- >>> > The deal.II project is located at http://www.dealii.org/ >>> > For mailing list/forum options, see >>> https://groups.google.com/d/forum/dealii?hl=en >>> > --- >>> > You received this message because you are subscribed to the Google >>> Groups "deal.II User Group" group. >>> > To unsubscribe from this group and stop receiving emails from it, send >>> an email to dealii+un...@googlegroups.com. >>> > To view this discussion on the web visit >>> https://groups.google.com/d/msgid/dealii/9741338e-2a31-418b-815d-277a5d7cb573n%40googlegroups.com. >>> >>> >>> > >>> > -- >>> > The deal.II project is located at http://www.dealii.org/ >>> > For mailing list/forum options, see >>> https://groups.google.com/d/forum/dealii?hl=en >>> > --- >>> > You received this message because you are subscribed to the Google >>> Groups "deal.II User Group" group. >>> > To unsubscribe from this group and stop receiving emails from it, send >>> an email to dealii+un...@googlegroups.com. >>> > To view this discussion on the web visit >>> https://groups.google.com/d/msgid/dealii/c2544a5b-16b0-4d3d-8ccc-22e77ccf3038n%40googlegroups.com. >>> >>> >>> >>> -- >> The deal.II project is located at http://www.dealii.org/ >> For mailing list/forum options, see >> https://groups.google.com/d/forum/dealii?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "deal.II User Group" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to dealii+un...@googlegroups.com. >> >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/dealii/697c9d76-0969-4c32-bd57-58371d02c21dn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/dealii/697c9d76-0969-4c32-bd57-58371d02c21dn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. 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