# Can we use nonuniform time steps to compute Caputo Fractional derivative in Heat equation FF++ code? (My code is runing but not good result comes)

**URL:** <https://community.freefem.org/t/can-we-use-nonuniform-time-steps-to-compute-caputo-fractional-derivative-in-heat-equation-ff-code-my-code-is-runing-but-not-good-result-comes/3887>\
**Category:** General Discussion\
**Created:** [April 28, 2025, 3:44am UTC](https://community.freefem.org/t/can-we-use-nonuniform-time-steps-to-compute-caputo-fractional-derivative-in-heat-equation-ff-code-my-code-is-runing-but-not-good-result-comes/3887 "2025-04-28T03:44:33Z")\
**Posts on this page:** 1\
**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:** [April 28, 2025, 3:44am UTC](https://community.freefem.org/t/can-we-use-nonuniform-time-steps-to-compute-caputo-fractional-derivative-in-heat-equation-ff-code-my-code-is-runing-but-not-good-result-comes/3887/1 "2025-04-28T03:44:33Z")

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Dear all, i want to know that can we use **nonuniform time steps in FreeFem++** to compute the following Caputo derivative for the fractional dervative in FreeFem++ ??

 ![Caputo_Frac](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/1/1efca09a612e558b488a1795a10344cc68c1bba7.png)

**What will its Codes format??.**

I have tried like the following way but not good results comes after initial time. I have implemented the nonuniform time step in Heat equation code. Code is running fine but results is not coming good.

Here, is my code:  
[Heat\_nonuniform\_timestep.edp](https://community.freefem.org/uploads/short-url/sQ5WWDnzXa6N6CYfP3iUoxkhOgp.edp) (3.2 KB)

Thanks in advance!.