# Operation error in problem definition

**URL:** <https://community.freefem.org/t/operation-error-in-problem-definition/466>\
**Category:** General Discussion\
**Created:** [June 13, 2020, 1:50pm UTC](https://community.freefem.org/t/operation-error-in-problem-definition/466 "2020-06-13T13:50:31Z")\
**Posts on this page:** 1\
**Showing post:** 18

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**Author:** ![sumantkr](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/sumantkr/32/2681_2.png) [@sumantkr](https://community.freefem.org/u/sumantkr)\
**Post date:** [August 29, 2020, 10:39am UTC](https://community.freefem.org/t/operation-error-in-problem-definition/466/18 "2020-08-29T10:39:24Z")

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Sir, based on the above discussion and suggestion given by you, I have implemented the parallel code on a few coupled equation and results have a good agreement with the final results.

Now, I am stuck in a mixed differential type coupled problem, for which I am not getting the error reducing with the iteration. I have created a post on [general discussion](https://community.freefem.org/t/newton-method-convergence-error/554) also.

I request you to kindly, suggest me regarding this issue.

Thansk

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