How to get derivative value at one specified point after solving the system

[沈键]

I met a problem that need constrain one point's gradient to zero vector. I found it's hard to give this constraint in deal.ii, so I change it to a optimization problem whose target is to minimize the given point's gradient magnitude to zero, but an another problem appeared, in each iteration, after solving the system  I need to evaluate the gradient at that point, and what I know is that point geometry coordinate. How can I get derivative value at specified point after solving the system? Thanks for your answer in advance!

[Daniel Arndt]

You can use VectorTools::point_gradient (https://www.dealii.org/current/doxygen/deal.II/namespaceVectorTools.html#af72dcb595cc262bec07ca5c81614586f) to obtain the gradient of a finite element solution in a specific point.

Best,

Daniel

Am Sa., 15. Mai 2021 um 23:05 Uhr schrieb 沈键 <sj20...@gmail.com>:

I met a problem that need constrain one point's gradient to zero vector. I found it's hard to give this constraint in deal.ii, so I change it to a optimization problem whose target is to minimize the given point's gradient magnitude to zero, but an another problem appeared, in each iteration, after solving the system  I need to evaluate the gradient at that point, and what I know is that point geometry coordinate. How can I get derivative value at specified point after solving the system? Thanks for your answer in advance!

--
The deal.II project is located at http://www.dealii.org/
For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en
---
You received this message because you are subscribed to the Google Groups "deal.II User Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to dealii+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/29d6d211-7a71-41f4-8121-5a413c4f4930n%40googlegroups.com.

[沈键]

Thank you, I solve my problem.