# Equivalent for assemble in dolfinx

**URL:** <https://fenicsproject.discourse.group/t/equivalent-for-assemble-in-dolfinx/10136>\
**Category:** dolfinx\
**Created:** [January 11, 2023, 2:56pm UTC](https://fenicsproject.discourse.group/t/equivalent-for-assemble-in-dolfinx/10136 "2023-01-11T14:56:46Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Cou](https://avatars.discourse-cdn.com/v4/letter/c/919ad9/32.png) [@Cou](https://fenicsproject.discourse.group/u/Cou)\
**Post date:** [January 11, 2023, 2:56pm UTC](https://fenicsproject.discourse.group/t/equivalent-for-assemble-in-dolfinx/10136/1 "2023-01-11T14:56:46Z")

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Hi,

I´m currently trying to port my code from Legacy FEniCS to FEniCS X.

I used sth. like

```auto
val = assemble(u_n*ds)

```

What’s the equivalent in FEniCS X?

Thanks!

---

<div class="post-metadata">

**Author:** ![nate](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/nate/32/17_2.png) [@nate](https://fenicsproject.discourse.group/u/nate)\
**Post date:** [January 11, 2023, 3:40pm UTC](https://fenicsproject.discourse.group/t/equivalent-for-assemble-in-dolfinx/10136/2 "2023-01-11T15:40:56Z")

</div>

See, for example, @dokken’s excellent [dolfinx tutorial](https://jsdokken.com/dolfinx-tutorial/index.html) for guides on updating your code.