# To find the Order of Convergence of the heat equation when exact solution is not given

**URL:** <https://community.freefem.org/t/to-find-the-order-of-convergence-of-the-heat-equation-when-exact-solution-is-not-given/3601>\
**Category:** General Discussion\
**Created:** [November 24, 2024, 3:11pm UTC](https://community.freefem.org/t/to-find-the-order-of-convergence-of-the-heat-equation-when-exact-solution-is-not-given/3601 "2024-11-24T15:11:47Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Monirul25](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/monirul25/32/3287_2.png) [@Monirul25](https://community.freefem.org/u/Monirul25)\
**Post date:** [November 24, 2024, 3:11pm UTC](https://community.freefem.org/t/to-find-the-order-of-convergence-of-the-heat-equation-when-exact-solution-is-not-given/3601/1 "2024-11-24T15:11:47Z")

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Hi, i am trying to find order of convergence of heat equation when exact solution is not given only data is given. My code is running but it is not giving optimal results. Can you help me please.

Here, is my code.  
[Heat\_twoD\_exact\_unkown.edp](https://community.freefem.org/uploads/short-url/3jAUxggOVqESqZ7VS49d22XtdFu.edp) (2.3 KB)

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**Author:** ![mhg](https://avatars.discourse-cdn.com/v4/letter/m/d07c76/32.png) [@mhg](https://community.freefem.org/u/mhg)\
**Post date:** [November 25, 2024, 12:09pm UTC](https://community.freefem.org/t/to-find-the-order-of-convergence-of-the-heat-equation-when-exact-solution-is-not-given/3601/2 "2024-11-25T12:09:45Z")

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Hi Monirul,  
if you do not have the exact solution, the best you can do is to check consistency by using an over-kill solution computed on a very fine mesh.

Another option is to construct a exact solution by the “method of manufactured solutions”.

Best,  
Michael

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**Author:** ![Monirul25](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/monirul25/32/3287_2.png) [@Monirul25](https://community.freefem.org/u/Monirul25)\
**Post date:** [November 25, 2024, 4:44pm UTC](https://community.freefem.org/t/to-find-the-order-of-convergence-of-the-heat-equation-when-exact-solution-is-not-given/3601/3 "2024-11-25T16:44:25Z")

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Thanks for you replies. Can you modify my code accordingly and send me. I have provided the code.