# Laplace value in freefem

**URL:** https://community.freefem.org/t/laplace-value-in-freefem/2371
**Category:** General Discussion
**Created:** [April 2, 2023, 7:22am UTC](https://community.freefem.org/t/laplace-value-in-freefem/2371 "2023-04-02T07:22:54Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![zese](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zese/32/917_2.png) [@zese](https://community.freefem.org/u/zese)
#### Post date: [April 2, 2023, 7:22am UTC](https://community.freefem.org/t/laplace-value-in-freefem/2371/1 "2023-04-02T07:22:54Z")

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Dear all

I have the values for (Ux,Ur,Utheta) and I want to calculate ((1/Re)Laplace(U)) for axisymmetric geometry. because of having y^2 as the denominator, its calculation is difficult. I wanted to use the following  
varf Laplace(unused,[wx,wr,wphi])=  
int2d(th)(2_pi_(1/Re)_y_(D(U).D(w)));

Xh A=Laplace(0,Xh);

where D=0.5\*(Grad(U)+GradT(U))

but I had error.

how I can drive it?

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<div class="post-metadata">

### Author: ![cmd](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/cmd/32/67_2.png) [@cmd](https://community.freefem.org/u/cmd)
#### Post date: [April 2, 2023, 7:58am UTC](https://community.freefem.org/t/laplace-value-in-freefem/2371/2 "2023-04-02T07:58:09Z")

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Can you replace `1/y` terms in `D(U)` with `1/(y +(y==0))` to remove the pole and let your BCs on the central axis handle the rest?