# \[Mixed-dimensional Branch\] Coupling Subdomain function with whole-domain function

**URL:** <https://fenicsproject.discourse.group/t/mixed-dimensional-branch-coupling-subdomain-function-with-whole-domain-function/8183>\
**Category:** Errors\
**Created:** [April 29, 2022, 11:05am UTC](https://fenicsproject.discourse.group/t/mixed-dimensional-branch-coupling-subdomain-function-with-whole-domain-function/8183 "2022-04-29T11:05:44Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![bbataszai](https://avatars.discourse-cdn.com/v4/letter/b/8c91f0/32.png) [@bbataszai](https://fenicsproject.discourse.group/u/bbataszai)\
**Post date:** [May 3, 2022, 9:30am UTC](https://fenicsproject.discourse.group/t/mixed-dimensional-branch-coupling-subdomain-function-with-whole-domain-function/8183/2 "2022-05-03T09:30:28Z")

</div>

Hi,  
Just a random guess… Have you tried to use `[...] + inner(grad(u2), u1)*v2*dx1(1)` instead of `[...] + inner(grad(u2), u1)*v2*dx2`? (Changed the measure). I had something similar [here](https://fenicsproject.discourse.group/t/unable-to-successfully-call-petsc-function-matsetvalueslocal/8172/5).

Concerning the newton solver… I am surely not an expert on this, sorry.  
Baltasar

---

_[View the full topic](https://fenicsproject.discourse.group/t/mixed-dimensional-branch-coupling-subdomain-function-with-whole-domain-function/8183)._