Dear Lucas, Great! We're looking forward to adding you to the list of contributors <https://www.dealii.org/authors.html> to the project :-)
J-P On Monday, August 28, 2017 at 5:42:30 PM UTC+2, Lucas Campos wrote: > > Dear Jean-Paul, > > I can definitely do it. > > Lucas > > On 28 August 2017 at 17:40, Jean-Paul Pelteret <> wrote: > >> Dear Lucas, >> >> You're welcome. Thanks for the discussion and your feedback! I've made a >> note to myself <https://github.com/dealii/dealii/issues/4979> to improve >> the documentation in this area, but if you want a small side-project then >> feel free to propose the amendments yourself with a pull request to the >> GitHub repository :-) I'd be happy to help you out if you want / need it. >> >> J-P >> >> On Monday, August 28, 2017 at 5:35:10 PM UTC+2, Lucas Campos wrote: >>> >>> Dear Jean-Paul, >>> >>> Thanks again. Now I do understand and it all makes sense. >>> >>> Also, while yes, I agree that the lack of the else could lead to errors >>> that quite hard to track down. However, I think adding your comment to that >>> part of the tutorial could save someone having the same issues I faced. >>> >>> Thanks for your time, >>> Lucas >>> >>> On 28 August 2017 at 17:26, Jean-Paul Pelteret <> wrote: >>> >>>> Hi Lucas, >>>> >>>> I see, now I understand to what you were referring. >>>> >>>> Yes, the specific example that you've shown here is an intentional >>>> redundancy. Previous experiences has shown that we all have a tendency to >>>> copy-paste the tutorials and work from them (that is their intended use >>>> after all :-). I put this in place to ensure that one doesn't accidentally >>>> forget the "else" case when refactoring this code. It would be very easy >>>> to >>>> do, and could be a tricky error to track down. Furthermore, it also >>>> reinforces what was discussed in the introductory paragraph above it. >>>> >>>> So I agree fully that this is not required. One could in fact reduce >>>> this entire implementation of the constraints to only a few lines. But in >>>> the interest of clarity it will remain in its current form for now :-) >>>> >>>> Regards, >>>> Jean-Paul >>>> >>>> On Monday, August 28, 2017 at 5:14:52 PM UTC+2, Lucas Campos wrote: >>>>> >>>>> Dear Jean-Paul, >>>>> >>>>> Thanks for your answer! Still, I am not sure if I understand the code. >>>>> The main issue seems to be that both blocks in every if else path are the >>>>> exactly the same. For instance, >>>>> >>>>> if (apply_dirichlet_bc == true) >>>>>> VectorTools::interpolate_boundary_values >>>>>> <http://dealii.org/developer/doxygen/deal.II/namespaceVectorTools.html#a9f3e3ae1396811f998cc35f94cbaa926> >>>>>> (dof_handler_ref, >>>>>> boundary_id, >>>>>> Functions::ZeroFunction<dim> >>>>>> <http://dealii.org/developer/doxygen/deal.II/classFunctions_1_1ZeroFunction.html> >>>>>> (n_components), >>>>>> constraints, >>>>>> fe.component_mask >>>>>> <http://dealii.org/developer/doxygen/deal.II/classFiniteElement.html#ace1f6cf0a9f0eb472be4df56743851aa> >>>>>> (x_displacement)); >>>>>> else >>>>>> VectorTools::interpolate_boundary_values >>>>>> <http://dealii.org/developer/doxygen/deal.II/namespaceVectorTools.html#a9f3e3ae1396811f998cc35f94cbaa926> >>>>>> (dof_handler_ref, >>>>>> boundary_id, >>>>>> Functions::ZeroFunction<dim> >>>>>> <http://dealii.org/developer/doxygen/deal.II/classFunctions_1_1ZeroFunction.html> >>>>>> (n_components), >>>>>> constraints, >>>>>> fe.component_mask >>>>>> <http://dealii.org/developer/doxygen/deal.II/classFiniteElement.html#ace1f6cf0a9f0eb472be4df56743851aa> >>>>>> (x_displacement)); >>>>>> >>>>> >>>>> What is the use of having if-else in this situation? >>>>> >>>>> Also, in your answer you mentioned that in the second call (iteration >>>>> == 1), only homogeneous constrains will be built. I also cannot see this >>>>> from the code. Perhaps this part is interacting with some other part of >>>>> the >>>>> code in a way I cannot see? >>>>> >>>>> Thanks for the help, >>>>> Lucas Campos >>>>> >>>>> On 28 August 2017 at 17:03, Jean-Paul Pelteret <> wrote: >>>>> >>>>>> Hi Lucas, >>>>>> >>>>>> So it sounds as if you've already worked out what's happening here. >>>>>> We consider 3 cases, namely what to do for newton iteration equal to 0, >>>>>> equal to 1, and greater than 1. >>>>>> >>>>>> For iteration == 0 and iteration == 1, the early return on line 2468 >>>>>> <https://github.com/dealii/dealii/blob/master/examples/step-44/step-44.cc?utf8=%E2%9C%93#L2468> >>>>>> >>>>>> is not satisfied and we have to build some dirichlet constraints. Which >>>>>> constraints are build is governed by the iteration number: if it is >>>>>> equal >>>>>> to zero, then apply_dirichlet_BC >>>>>> <https://github.com/dealii/dealii/blob/master/examples/step-44/step-44.cc?utf8=%E2%9C%93#L2471> >>>>>> >>>>>> is set true and we build non-homogeneous constraints (the "if" case). On >>>>>> the next visit to this function (iteration == 1) this flag is set to >>>>>> false >>>>>> and we build only homogeneous constraints (the "else" case). At >>>>>> subsequent >>>>>> iterations we use the early return that I previously mentioned to make >>>>>> no >>>>>> further changes to the existing constraint matrix. This is because it is >>>>>> already filled with the homogeneous constraints, which is what we want >>>>>> for >>>>>> all newton iterations > 0. >>>>>> >>>>>> Does this make sense? >>>>>> >>>>>> Regards, >>>>>> Jean-Paul >>>>>> >>>>>> On Monday, August 28, 2017 at 4:14:31 PM UTC+2, Lucas Campos wrote: >>>>>>> >>>>>>> > This calculation does not happen anyway, because of the early >>>>>>> return in line 2466. >>>>>>> >>>>>>> Just a minor correction for the previous sentence: The guard on line >>>>>>> 2466 will be true only on the second iterations. The else paths will >>>>>>> still >>>>>>> be taken at least once. >>>>>>> >>>>>>> On Monday, 28 August 2017 16:02:01 UTC+2, Lucas Campos wrote: >>>>>>>> >>>>>>>> Dear all, >>>>>>>> >>>>>>>> First of all, thanks for the great library! I spent the last few >>>>>>>> days reading your (very!) extensive >>>>>>>> documentation and I think it will be really useful for me in the >>>>>>>> near future. >>>>>>>> >>>>>>>> Right now I am struggling a bit on understanding some things on >>>>>>>> step-44. Most pressing right >>>>>>>> now is that, in Section Solid::make_constraints of the tutorials, >>>>>>>> we have >>>>>>>> >>>>>>>> > However, since we are dealing with an iterative Newton method, >>>>>>>> it should be noted >>>>>>>> > that any displacement constraints should only be specified at the >>>>>>>> zeroth iteration >>>>>>>> > and subsequently no additional contributions are to be made since >>>>>>>> the constraints >>>>>>>> > are already exactly satisfied. >>>>>>>> >>>>>>>> However, reading the code underneath, the code under the if-else >>>>>>>> blocks are the same (around >>>>>>>> line 2490 of step-44.cc). That is to say, we would run the same >>>>>>>> computation whether the condition >>>>>>>> is true or false. This calculation does not happen anyway, because >>>>>>>> of the early return in line 2466. >>>>>>>> If we disregard this early return, would this code be wrong, or is >>>>>>>> there something I am not seeing? >>>>>>>> >>>>>>>> Bests, >>>>>>>> Lucas >>>>>>>> >>>>>>> -- >>>>>> 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 a topic in >>>>>> the Google Groups "deal.II User Group" group. >>>>>> To unsubscribe from this topic, visit >>>>>> https://groups.google.com/d/topic/dealii/TSUwtKqcotY/unsubscribe. >>>>>> To unsubscribe from this group and all its topics, send an email to >>>>>> dealii+unsubscr...@googlegroups.com. >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> -- >>>> 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 a topic in the >>>> Google Groups "deal.II User Group" group. >>>> To unsubscribe from this topic, visit >>>> https://groups.google.com/d/topic/dealii/TSUwtKqcotY/unsubscribe. >>>> To unsubscribe from this group and all its topics, send an email to >>>> dealii+unsubscr...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> 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 a topic in the >> Google Groups "deal.II User Group" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/dealii/TSUwtKqcotY/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> dealii+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > > -- 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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