# WiFi Propagation example errors

**URL:** <https://community.freefem.org/t/wifi-propagation-example-errors/941>\
**Category:** General Discussion\
**Created:** [April 24, 2021, 1:11pm UTC](https://community.freefem.org/t/wifi-propagation-example-errors/941 "2021-04-24T13:11:14Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![LiudasD](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/liudasd/32/523_2.png) [@LiudasD](https://community.freefem.org/u/LiudasD)\
**Post date:** [April 24, 2021, 1:11pm UTC](https://community.freefem.org/t/wifi-propagation-example-errors/941/1 "2021-04-24T13:11:14Z")

</div>

Hello,

I’m trying to execute example from [Wifi Propagation](https://doc.freefem.org/tutorials/wifiPropagation.html), but I get errors:

```
 Error umpfack umfpack_zi_numeric status 1
 Error umfpack_di_solve status 1
  -- Solve : 
          min (-0.13597,-0.169774) max (1,0.106414)

```

To run exampe I’m using docker image:

docker run -v $(pwd):/data freefem/freefem /bin/bash -c “cd /data; FreeFem++ /data/wifi.edp”  
(I’m running it this way to change directory first and the run scrips to be able to save \*.ps files in local directory)

One more thing, I had to change this part too to avoid errors:  
From:  
cout \<\< "Reflexion of walls : " \<\< wallreflexion \<\< “\n”;  
cout \<\< "Absorption of walls : " \<\< wallabsorption \<\< “\n”;

```
To:
cout << "Reflexion of walls : " << wallreflexion[] << "\n";
cout << "Absorption of walls : " << wallabsorption[] << "\n";

```

Can anyone share working example? or guide me where to find errors?

Thank you for the help

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<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [April 25, 2021, 6:03am UTC](https://community.freefem.org/t/wifi-propagation-example-errors/941/2 "2021-04-25T06:03:37Z")

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I have do this correction,  
print the min/max not the array

[wifi.edp](https://community.freefem.org/uploads/short-url/g7P4Gw6W5XVF1FsGChcFgQ1xrAF.edp) (2.2 KB)  
an this example run on macOS .

You cn increase the verbosity to see all the step of umfpack, and/or change of linear system (load “MUMPS”)

---

<div class="post-metadata">

**Author:** ![LiudasD](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/liudasd/32/523_2.png) [@LiudasD](https://community.freefem.org/u/LiudasD)\
**Post date:** [April 25, 2021, 8:01am UTC](https://community.freefem.org/t/wifi-propagation-example-errors/941/3 "2021-04-25T08:01:08Z")

</div>

Thank you, it works both on macOS and Docker container.