Derivatives of gradients

[Alex Lindsay]

Hi all, I have the following problem. I am trying to set-up the Jacobian matrix for a finite element problem in a different software package and I need to compute some partial derivatives like the one below:


In order to evaluate this I need sympy to be able to do the following relationship:


If it's possible, how might I go about implementing this?

Alex

[Alex Lindsay]

I realized that what I wrote here is nonsensical. I can't commute partial / partial_u through the gradient operator! Silly me