[USER=2]Jorgen[/USER] , wouldnt this Toolbox be great for your Book to simplify the code for your Neo-Hookean UMAT Subroutine? You can have a look for...

[B]Update:[/B] The Toolbox is more or less finished now 🙂 - every feature is tested and I encountered no errors so far. If someone is interested how...

Please do not use Voigt notation as its implementation is currently wrong. Ill report back when I have fixed it. EDIT: Fixed! Modified double dot prod...