# Optimal coefficient in movemesh

**URL:** <https://community.freefem.org/t/optimal-coefficient-in-movemesh/706>\
**Category:** General Discussion\
**Created:** [December 24, 2020, 7:20am UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706 "2020-12-24T07:20:42Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Sunrise](https://avatars.discourse-cdn.com/v4/letter/s/9fc29f/32.png) [@Sunrise](https://community.freefem.org/u/Sunrise)\
**Post date:** [December 24, 2020, 7:20am UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706/1 "2020-12-24T07:20:42Z")

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Dear all, how to choose the optimal coefficient ‘dt’ when moving a mesh  
Th = movemesh(Th,[x+dt_vx,y+dt_vy]);  
Thank you in advance!

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**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [December 24, 2020, 7:34am UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706/2 "2020-12-24T07:34:55Z")

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Well, there is no optimal value… it all depends on how _you_ want to move the mesh.

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**Author:** ![Sunrise](https://avatars.discourse-cdn.com/v4/letter/s/9fc29f/32.png) [@Sunrise](https://community.freefem.org/u/Sunrise)\
**Post date:** [December 26, 2020, 6:14pm UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706/3 "2020-12-26T18:14:48Z")

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I am looking for a domain realizing the minimum of a function in a “shape optimization problem”  
and I am trying to use a line search method

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<div class="post-metadata">

**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [December 26, 2020, 7:48pm UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706/4 "2020-12-26T19:48:44Z")

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Then your optimization algorithm should give you the proper value for `dt`.

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**Author:** ![Sunrise](https://avatars.discourse-cdn.com/v4/letter/s/9fc29f/32.png) [@Sunrise](https://community.freefem.org/u/Sunrise)\
**Post date:** [December 27, 2020, 7:42pm UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706/5 "2020-12-27T19:42:38Z")

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The algorithm gives only the deformation field (vx, vy)