# Cannot get example to work

**URL:** <https://community.freefem.org/t/cannot-get-example-to-work/574>\
**Category:** General Discussion\
**Created:** [September 6, 2020, 9:22pm UTC](https://community.freefem.org/t/cannot-get-example-to-work/574 "2020-09-06T21:22:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dajopez](https://avatars.discourse-cdn.com/v4/letter/d/a87d85/32.png) [@dajopez](https://community.freefem.org/u/dajopez)\
**Post date:** [September 6, 2020, 9:22pm UTC](https://community.freefem.org/t/cannot-get-example-to-work/574/1 "2020-09-06T21:22:56Z")

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I am trying to mess with example code, but when I copy and paste into the online compiler it throws an error. It doesn’t like Line 40

int k = EigenValue(OP, B, sym=true, sigma=sigma, value=ev, vector=eV,  
tol=1e-10, maxit=0, ncv=0);

Everything runs up until that point. The example is Eigenfucntion of the shifted laplacian on the square. Any ideas what is going on?

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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:** [September 8, 2020, 4:11am UTC](https://community.freefem.org/t/cannot-get-example-to-work/574/2 "2020-09-08T04:11:37Z")

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Which “online compiler”?