# How to solve a problem based on 2D polar coordinate

**URL:** <https://community.freefem.org/t/how-to-solve-a-problem-based-on-2d-polar-coordinate/2062>\
**Category:** General Discussion\
**Created:** [October 15, 2022, 2:42am UTC](https://community.freefem.org/t/how-to-solve-a-problem-based-on-2d-polar-coordinate/2062 "2022-10-15T02:42:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Kellen](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@Kellen](https://community.freefem.org/u/Kellen)\
**Post date:** [October 15, 2022, 2:42am UTC](https://community.freefem.org/t/how-to-solve-a-problem-based-on-2d-polar-coordinate/2062/1 "2022-10-15T02:42:56Z")

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Hello, everyone. I’m solving a problem in a domain which is reprensted with polar coordinate. The equation is given in rectangular coordinate system. But the Dirichlet boundary condition is polar coordinate. So I think I should solve this equation in polar coordinate. But I don’t know if freefem can solve 2D coordinate equations. If the answer is yes, how should the two polar variables be represented in freefem. I’m looking forward to receiving your reply. Thank you very much!

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<div class="post-metadata">

**Author:** ![galfras](https://avatars.discourse-cdn.com/v4/letter/g/898d66/32.png) [@galfras](https://community.freefem.org/u/galfras)\
**Post date:** [October 15, 2022, 5:18pm UTC](https://community.freefem.org/t/how-to-solve-a-problem-based-on-2d-polar-coordinate/2062/2 "2022-10-15T17:18:59Z")

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Page 52 of the FreeFem++ Documentation talks about the polar coordinate system. Here is an exaple of how the Laplace operator is defined:

```auto
problem thermaxi(u, v)
 = int2d(Th)(
 (u*v/dt + dx(u)*dx(v) + dy(u)*dy(v))*x
 )
 + int1d(Th, 3)(
 alpha*x*u*v
 )
 - int1d(Th, 3)(
 alpha*x*ue*v
 )
 - int2d(Th)(
 uold*v*x/dt
 )
 + on(2, 4, u=u0);

```