# Can't create the solution for waveguide.edp **URL:** \ **Category:** General Discussion\ **Created:** [February 16, 2023, 1:47am UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282 "2023-02-16T01:47:48Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![Box1](https://avatars.discourse-cdn.com/v4/letter/b/f07891/32.png) [@Box1](https://community.freefem.org/u/Box1)\ **Post date:** [July 27, 2025, 5:26pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/21 "2025-07-27T17:26:50Z")
Thank you for your response. I have version 4.15. I also tried uninstalling and reinstalling version 4.15, and re-launching the `waveguide.edp` file, but the results are the same. I really don’t know why. May I ask which version of FreeFem++ you are currently using? Or could the problem be that I don’t have sufficient RAM to handle this task? I’m using an Intel Core i7-13620H, but there’s no indication of an “out of memory” error.. Thank you once again ---
**Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\ **Post date:** [July 27, 2025, 5:50pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/22 "2025-07-27T17:50:11Z")
I have tried version 4.14 on one computer, and 4.15 on another one (linux ubuntu and linux debian). Both work normally, even if I replace “solver=sparsesolver” by “solver=umfpack”. This is probably due to your computer or your installation (in particular umfpack) (?) ---
**Author:** ![Box1](https://avatars.discourse-cdn.com/v4/letter/b/f07891/32.png) [@Box1](https://community.freefem.org/u/Box1)\ **Post date:** [July 27, 2025, 6:16pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/23 "2025-07-27T18:16:35Z")
ok, I tried with “solver=umfpack” and this was the result: ```auto 71 : problem waveguide([Ex,Ey,Ez], [vx,vy,vz], solver=umfpack The Identifier umfpack does not exist Error line number 71, in file C:\Users\giorg\Desktop\waveguide.edp, before token umfpack current line = 71 Compile error : line number :71, umfpack error Compile error : line number :71, umfpack code = 1 mpirank: 0 try getConsole C:\Users\giorg\Desktop\waveguide.edp save log in : 'C:\Users\giorg\Desktop\waveguide.log' wait enter ? ``` I think I’m missing something. I tried this program on three different PCs, all running Windows 11. I tested both version 4.15 Win64 and version 4.15-b Win64. Have you installed any plugins? ---
**Author:** ![Box1](https://avatars.discourse-cdn.com/v4/letter/b/f07891/32.png) [@Box1](https://community.freefem.org/u/Box1)\ **Post date:** [July 27, 2025, 6:59pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/24 "2025-07-27T18:59:41Z")
SOLVED: the problem was here: ```auto real f = 94*10^9; ``` which I changed to: ```auto real f = 94e9; ``` Now the result is correct and is exatly the same as yours. I also tried adding: ```auto cout<<94*10^9< **Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\ **Post date:** [July 27, 2025, 7:15pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/25 "2025-07-27T19:15:13Z") I was not precise enough, you have to put `solver="UMFPACK"` You have the UMFPACK, since you had the error message “UMFPACK WARNING singular matrix”. This is the mysterious point: the matrix should not be singular. ---
**Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\ **Post date:** [July 27, 2025, 7:23pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/26 "2025-07-27T19:23:11Z")
Great that you solved it. It seems that the right-hand side was exceeding the capacity of your computer in terms of integers. Then converting this integer to real gives a wrong value. Maybe your computer installation is 32bit ? You bypass the problem by defining it directly as a real number. ---
**Author:** ![Box1](https://avatars.discourse-cdn.com/v4/letter/b/f07891/32.png) [@Box1](https://community.freefem.org/u/Box1)\ **Post date:** [July 27, 2025, 9:05pm UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/27 "2025-07-27T21:05:21Z")
Ah, I understand :). Regarding the installation, I really don’t know. I checked out both my windows version and FreeFem++ version, they’re both in 64 bit. Thank you so much for your help. Have a good night and a great start to the week! 🙂 ---
**Author:** ![alh](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/alh/32/2354_2.png) [@alh](https://community.freefem.org/u/alh)\ **Post date:** [July 28, 2025, 6:45am UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/28 "2025-07-28T06:45:35Z")
Hi. Your FreeFem version is fine. This is a difference between the Windows and Linux data models, LLP64 and LP64. “long int” are 32 bits under Windows and 64 under Linux (more info at [https://en.wikipedia.org/wiki/64-bit\_computing#64-bit\_data\_models](https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models) and [https://www.ljll.fr/lehyaric/ffcs/src/ffref/Basic/precision.m4.htm](https://www.ljll.fr/lehyaric/ffcs/src/ffref/Basic/precision.m4.htm)). Your solution with real numbers is good. ---
**Author:** ![Box](https://avatars.discourse-cdn.com/v4/letter/b/b19c9b/32.png) [@Box](https://community.freefem.org/u/Box)\ **Post date:** [July 29, 2025, 8:08am UTC](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282/29 "2025-07-29T08:08:36Z")
Thank you so much for the response and the interesting informations 🙂 [Previous page](https://community.freefem.org/t/cant-create-the-solution-for-waveguide-edp/2282.md?page=1)