# Cross derivatives implementation in FEniCS

**URL:** <https://fenicsproject.discourse.group/t/cross-derivatives-implementation-in-fenics/4487>\
**Category:** variational formulation\
**Created:** [November 3, 2020, 5:50pm UTC](https://fenicsproject.discourse.group/t/cross-derivatives-implementation-in-fenics/4487 "2020-11-03T17:50:11Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![dokken](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/dokken/32/1560_2.png) [@dokken](https://fenicsproject.discourse.group/u/dokken)\
**Post date:** [November 3, 2020, 6:20pm UTC](https://fenicsproject.discourse.group/t/cross-derivatives-implementation-in-fenics/4487/2 "2020-11-03T18:20:04Z")

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Integrate them by parts and use the Function.dx operator as shown in [Expressions depending on spatially varying coefficients and their derivatives in advection-diffusion-PDE](https://fenicsproject.discourse.group/t/expressions-depending-on-spatially-varying-coefficients-and-their-derivatives-in-advection-diffusion-pde/4441/4)

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