# Curl computation

**URL:** <https://community.freefem.org/t/curl-computation/1028>\
**Category:** General Discussion\
**Created:** [June 13, 2021, 8:22am UTC](https://community.freefem.org/t/curl-computation/1028 "2021-06-13T08:22:58Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Dua](https://avatars.discourse-cdn.com/v4/letter/d/c37758/32.png) [@Dua](https://community.freefem.org/u/Dua)\
**Post date:** [June 13, 2021, 8:22am UTC](https://community.freefem.org/t/curl-computation/1028/1 "2021-06-13T08:22:58Z")

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Hello every one,

I have a problem when I want to compute Curl of my function,  
fespace Rh(Th, Edge03d);  
Rh [lxx, lyy, lzz];  
func lx= x^2;  
func ly= x^2+3+y;  
func lz= 5.;  
[lxx,lyy,lzz]= 2\*Curl(lx,ly,lz);

It gives me an error : dy(lz) error operator, do you know what is the problem?

Thanks.

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<div class="post-metadata">

**Author:** ![julienG](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/julieng/32/222_2.png) [@julienG](https://community.freefem.org/u/julienG)\
**Post date:** [June 13, 2021, 9:54am UTC](https://community.freefem.org/t/curl-computation/1028/2 "2021-06-13T09:54:20Z")

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I think the differentiation `dx()` works only on `fespace` function.  
Here you apply it to `func`