# Modifying the jacobian determinant of some mesh elements

**URL:** <https://fenicsproject.discourse.group/t/modifying-the-jacobian-determinant-of-some-mesh-elements/17834>\
**Category:** General\
**Tags:** mesh, dolfinx\
**Created:** [June 24, 2025, 1:12pm UTC](https://fenicsproject.discourse.group/t/modifying-the-jacobian-determinant-of-some-mesh-elements/17834 "2025-06-24T13:12:00Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![pa-beaufort](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/pa-beaufort/32/7925_2.png) [@pa-beaufort](https://fenicsproject.discourse.group/u/pa-beaufort)\
**Post date:** [June 24, 2025, 1:12pm UTC](https://fenicsproject.discourse.group/t/modifying-the-jacobian-determinant-of-some-mesh-elements/17834/1 "2025-06-24T13:12:00Z")

</div>

Hello.

I would like to define a threshold on the jacobian determinants such that the effective determinant for a quadrature over an element is  
|J\_{effective}| = \max( |J\_{element}|, \epsilon )  
where \epsilon \> 0 is an arbitrary threshold.

How shall I proceed?

The [PML example](https://docs.fenicsproject.org/dolfinx/v0.6.0/python/demos/demo_pml.html#) does seem to correspond to my need, since it change the coordinate system, which might fail in the case of |J\_{element}| \<\< \epsilon .