Ok great, I'm glad that you're getting somewhere. So lets try to get to the bottom of this indexing issue (as a side note, and in case anyone else is interested, in this issue <https://github.com/dealii/dealii/issues/3646> we've started discussing how to document the index-related functions in a bit more detail).
Can I ask a quick question: Are you familiar with the step-8 <https://dealii.org/8.4.1/doxygen/deal.II/step_8.html> tutorial? This is the tutorial that details how vector-valued shape functions work in deal.II, and also what it means to ask (without the help of an extractor) for the gradient of one (primitive) shape function associated with a vector field. Although the tutorial described an application in solid mechanics, exactly the same concepts apply in your scenario. I think that this should give more insight into how one might go from the weak general form to a explicit assembly pseudo-code for a vector valued field. Its also better explained than anything that I could fit into this text-box, but if you don't find that to be the case then I've also expanded on it in this PDF <https://github.com/jppelteret/code-gallery/blob/353c02d31d76fdd76851a7313681d4d8bd1c42f4/Linear_Elastic_Active_Skeletal_Muscle_Model/doc/theory/theory-linear_elastic_active_muscle_model.pdf> (from page 5 is relevant). Using the extractors means that you (typically) don't have to worry about the manual component indexing via calls to const unsigned int component_i = fe.system_to_component_index <https://dealii.org/developer/doxygen/deal.II/classFiniteElement.html#a27220a135402b96c7e6eecbb04acda56> (i).first; This allows one to get, for a primitive vector shape function, its only spatial component that is non-zero. The extractors help by filtering out the shape functions associated with other fields and reinterprets and collects the shape function value/gradient information for the given field. -- 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+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
