# Error in a program

**URL:** <https://community.freefem.org/t/error-in-a-program/697>\
**Category:** General Discussion\
**Created:** [December 20, 2020, 12:22pm UTC](https://community.freefem.org/t/error-in-a-program/697 "2020-12-20T12:22:44Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Aicha](https://avatars.discourse-cdn.com/v4/letter/a/ec9cab/32.png) [@Aicha](https://community.freefem.org/u/Aicha)\
**Post date:** [December 20, 2020, 12:22pm UTC](https://community.freefem.org/t/error-in-a-program/697/1 "2020-12-20T12:22:44Z")

</div>

Hi,  
i try to program with FF+ the following algo

 ![Capture](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/1X/aa104a8f423bc23226dac0d9940354ca2941cc42.png)  
i write the followin code but the problem is that i obtain zeo in each step.  
Can any one help me to find theproblem in my progam? Please.

[code.edp](https://community.freefem.org/uploads/short-url/nzevHDjObImVk4ADyiGPstGr0is.edp) (1.4 KB)

---

<div class="post-metadata">

**Author:** ![denis.crete](https://avatars.discourse-cdn.com/v4/letter/d/9d8465/32.png) [@denis.crete](https://community.freefem.org/u/denis.crete)\
**Post date:** [December 21, 2020, 10:44pm UTC](https://community.freefem.org/t/error-in-a-program/697/2 "2020-12-21T22:44:05Z")

</div>

Does the variable Idh need to be initialized (around Idh=2) ?  
HTH  
Denis