# Question on command

**URL:** <https://forum.itascainternational.com/t/question-on-command/1278>\
**Category:** PFC\
**Created:** [December 20, 2023, 11:04pm UTC](https://forum.itascainternational.com/t/question-on-command/1278 "2023-12-20T23:04:56Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Mussie](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/mussie/32/360_2.png) [@Mussie](https://forum.itascainternational.com/u/Mussie)\
**Post date:** [December 20, 2023, 11:04pm UTC](https://forum.itascainternational.com/t/question-on-command/1278/1 "2023-12-20T23:04:56Z")

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Hi everyone,  
I came across a command within the “Genesis and Testing of a Soft-Bonded Material” example where the command line “model domain tolerance 1e-3” was used. Unfortunately I was not able to understand what this means as _model domain tolerance_ was not listed in the manual. Does anyone know what this stands for?

Regards  
Mussie

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**Author:** ![dblanksma](https://avatars.discourse-cdn.com/v4/letter/d/858c86/32.png) [@dblanksma](https://forum.itascainternational.com/u/dblanksma)\
**Post date:** [January 5, 2024, 5:28pm UTC](https://forum.itascainternational.com/t/question-on-command/1278/2 "2024-01-05T17:28:35Z")

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Hello @Mussie,  
The tolerance keyword is a factor for updating domain based on how much the domain distorts. I’ll have our PFC developers update the documentation to include this keyword.

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**Author:** ![Mussie](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/mussie/32/360_2.png) [@Mussie](https://forum.itascainternational.com/u/Mussie)\
**Post date:** [January 5, 2024, 8:28pm UTC](https://forum.itascainternational.com/t/question-on-command/1278/3 "2024-01-05T20:28:50Z")

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Thank you very much @dblanksma!

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**Author:** ![LJYpyu](https://avatars.discourse-cdn.com/v4/letter/l/7cd45c/32.png) [@LJYpyu](https://forum.itascainternational.com/u/LJYpyu)\
**Post date:** [January 15, 2024, 3:51pm UTC](https://forum.itascainternational.com/t/question-on-command/1278/5 "2024-01-15T15:51:52Z")

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Hello @dblanksma,  
Actually I met some problem when I try to post my own topic, so I have to display my content here first because I find this approach works. Sorry for this operation and potential inconvenience. Indeed I find some interesting things.  
I find some weird things that the “solve time 2.0” is not equal to “solve time 1.0” + solve time 1.0" in some cases even though I use the fix timestep and ‘cycle’ to control. The following are my test results about plate load on particle assemble(r=0.05m) where the linear contact model is adopted and the F-z(force-displacement) is used to reflect the results. I set different load strategies including “solve time 5.0”, “solve time 2.5” + “solve time 2.5”, and “solve time 2.0” + “solve time 2.0” + “solve time 1.0”. and the following are the results.  
 ![image](https://canada1.discourse-cdn.com/flex031/uploads/itasca/original/1X/6d7aa05fe54cefbe6b089cf3f5ea1f4c298fe4ef.png)  
as you can see, the results are not completely coincident(the left Fig). Even though I used fixed timestep and cycle number(the right Fig), there’s still some difference  
so, what’s the reason? maybe this is not ordinary for an explicit calculation process. is this related to the chaotic and instability?  
In addition, when I use the cubic assemble to do the same test, this phenomena will disappear. All the test script is available.

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**Author:** ![jwang](https://avatars.discourse-cdn.com/v4/letter/j/b782af/32.png) [@jwang](https://forum.itascainternational.com/u/jwang)\
**Post date:** [January 16, 2024, 3:19pm UTC](https://forum.itascainternational.com/t/question-on-command/1278/6 "2024-01-16T15:19:07Z")

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Hello, you request has been approved and you can post a new topic now.