# Question about section 2.18 in the documentation

**URL:** https://community.freefem.org/t/question-about-section-2-18-in-the-documentation/2675
**Category:** General Discussion
**Created:** [August 31, 2023, 11:39am UTC](https://community.freefem.org/t/question-about-section-2-18-in-the-documentation/2675 "2023-08-31T11:39:48Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![jna1g18](https://avatars.discourse-cdn.com/v4/letter/j/77aa72/32.png) [@jna1g18](https://community.freefem.org/u/jna1g18)
#### Post date: [August 31, 2023, 11:39am UTC](https://community.freefem.org/t/question-about-section-2-18-in-the-documentation/2675/1 "2023-08-31T11:39:48Z")

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Hi all, section 2.18 (Tutorial to write a transient Stokes solver in matrix form) seems like it could be quite useful to me, but it does not show the original form of the PDE problem. For me to learn properly, it would be extremely useful if I knew the original problem, so before I try to work backwards from the code provided, is there anyone who can tell me the original form of this PDE problem?

Many thanks!