I need to express $\nabla = (\partial_x,\partial_y,\partial_z)$ as a vector, so that I can compute the differential operator given by $A\cdot\nabla$ (where here $A$ is a 3x3 matrix) using Mathematica. Subsequently, I need to be able to do operations with $\nabla_A := A \cdot \nabla$ on a vector/scalar and get the differential operator applied to the vector/scalar (e.g. either $\nabla_A\cdot \vec{v}$ or $\nabla_A \vec{v}$ or $\nabla_A \sigma$, where $\vec{v} \in \mathbb{R}^3$ and $\sigma \in \mathbb{R}$).

This comes down to treating $\nabla$ as a vector, which isn't allowed (as far as I can tell) by the Grad[-] function in Mathematica.

After browsing the documentation and forums, I couldn't figure out an easy way to try to do this. I am new to Mathematica, so any help is greatly appreciated!

  • $\begingroup$ Your question may be put on-hold because it may be considered a duplicate and therefore off-topic. Please edit your question if you consider this is a mistake and give great emphasis in what was NOT answered in the other question. Please don't be discouraged by that cleaning-up policy. Your questions are and will be most welcomed. Learn about good questions here. $\endgroup$ – rhermans May 31 '18 at 8:03
  • $\begingroup$ If the other question does contain the answer you were looking for, do let us know in the comments. $\endgroup$ – rhermans May 31 '18 at 8:05
  • $\begingroup$ It does, thanks! Sorry it was a dupilcate $\endgroup$ – Fishy Jun 5 '18 at 0:46