Random seed not being set in param card?

Asked by Radha Mastandrea on 2021-01-11

I am trying to set madgraph's random seed at the launch command, i.e. I run "launch", then edit the run card. However, when I do this and check the output file/Cards/run_card.dat, then random seed in that run card is still set to 0 (the default value) and I can find no indication that my manually setting the random seed did anything. This is with the generic madgraph settings (standard model) with generate p p > j j j.

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MadGraph5_aMC@NLO Edit question
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Last query:
2021-01-11
Last reply:
2021-01-11

Hi,

Yes this is normal.
The idea is that as soon as your seed is used, the run_card is reset to seed value to zero
such that you can do launch multiple times in a row and producing multiple independent result.

The way it works in MG5aMC is that we store in the direcotory the last value of the seed that was used
 and if the run_card has as seed 0, we increase the seed (by a fix number) and use that seed.

If you want to know the seed that you used for a given run, you need to read the banner asociated to this run.
You can find the banner as the top part of the lhe file generated but also as a text file with path like
Events/run_01/run_01_banner.txt

Cheers,

Olivier

> On 11 Jan 2021, at 16:15, Radha Mastandrea <email address hidden> wrote:
>
> New question #694896 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/694896
>
> I am trying to set madgraph's random seed at the launch command, i.e. I run "launch", then edit the run card. However, when I do this and check the output file/Cards/run_card.dat, then random seed in that run card is still set to 0 (the default value) and I can find no indication that my manually setting the random seed did anything. This is with the generic madgraph settings (standard model) with generate p p > j j j.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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