# Grad(u) to numpy array

**URL:** <https://fenicsproject.discourse.group/t/grad-u-to-numpy-array/4698>\
**Category:** Linear Algebra\
**Created:** [December 8, 2020, 7:19pm UTC](https://fenicsproject.discourse.group/t/grad-u-to-numpy-array/4698 "2020-12-08T19:19:44Z")\
**Posts on this page:** 1\
**Showing post:** 9

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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:** [May 6, 2023, 12:43pm UTC](https://fenicsproject.discourse.group/t/grad-u-to-numpy-array/4698/9 "2023-05-06T12:43:56Z")

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See my comment at: [How to compute the strain & stress matrices? - #7 by dokken](https://fenicsproject.discourse.group/t/how-to-compute-the-strain-stress-matrices/2756/7)

You can also use DOLFINx Expression for this purpose.  
In particular, use: [dolfinx/function.py at 9548c27e45bd0ca78d351964820cc4a4a7c0957d · FEniCS/dolfinx · GitHub](https://github.com/FEniCS/dolfinx/blob/9548c27e45bd0ca78d351964820cc4a4a7c0957d/python/dolfinx/fem/function.py#L171)  
[dolfinx/test\_expression.py at 9548c27e45bd0ca78d351964820cc4a4a7c0957d · FEniCS/dolfinx · GitHub](https://github.com/FEniCS/dolfinx/blob/9548c27e45bd0ca78d351964820cc4a4a7c0957d/python/test/unit/fem/test_expression.py#L354)

You could also have a look at  
[https://jsdokken.com/fenics22-tutorial/heat\_eq.html#post-processing-without-projections](https://jsdokken.com/fenics22-tutorial/heat_eq.html#post-processing-without-projections)

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