# Solution become unbounded

**URL:** <https://community.freefem.org/t/solution-become-unbounded/3710>\
**Category:** General Discussion\
**Created:** [January 26, 2025, 4:09pm UTC](https://community.freefem.org/t/solution-become-unbounded/3710 "2025-01-26T16:09:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kallol](https://avatars.discourse-cdn.com/v4/letter/k/59ef9b/32.png) [@kallol](https://community.freefem.org/u/kallol)\
**Post date:** [January 26, 2025, 4:09pm UTC](https://community.freefem.org/t/solution-become-unbounded/3710/1 "2025-01-26T16:09:41Z")

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I am trying to solve wave equation in FreeFem using standard finite element. Due to the source term the approximate solution become unbounded. Can anyone tell me why is this happening? I am attaching the code here. Thanks in advance.  
[wave 2.edp](https://community.freefem.org/uploads/short-url/nYNtAfy2NIi6f0i4NYWJlWarUya.edp) (2.5 KB)

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<div class="post-metadata">

**Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\
**Post date:** [January 27, 2025, 8:47am UTC](https://community.freefem.org/t/solution-become-unbounded/3710/2 "2025-01-27T08:47:06Z")

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Debug:  
line 74 `u1=uexact(0)` → `u1=uexact(dt)`  
line 89 `u=uexact(0)` → `u=uexact(t)`  
line 84 missing `dt^2`  
[wave2.edp](https://community.freefem.org/uploads/short-url/A49OPhu6kQgKeBPo4AwM2eRZRJu.edp) (2.5 KB)