Hope for detailed tutorial about how to obtain weak derivative?

[ouening]

Hi, FreeFem++ is a good start for learning FEM. But I think it's difficult to use it to solve custom problem. The biggest problem is converting regular PDE forms to the variational formulation. I have read some texts like https://www.math.tu-berlin.de/fileadmin/i26_ng-schmidt/Vorlesungen/IntroductionFEM_SS14/Chap2.pdf, but that's too hard for me to understand. I hope for the detailed and easy-understanding tutorial about how to obtain a variational formulation on a custom model. Thanks!

[fotios-kasolis]

An educational exposition regarding variational boundary value problems can be found https://github.com/hplgit/fem-book/tree/master/doc/pub/book/pdf.