MadGraph5_aMC@NLO

regarding systematics in madgraph

Asked by Disha Bhatia

Hi,

I was trying to run the madgraph output to generate systematics to my process.
However there is an error coming while running of madgraph and it is:
Failed to access python version of LHAPDF: If the python interface to LHAPDF is available on your system, try adding its location to the PYTHONPATH environment variable and theLHAPDF library location to LD_LIBRARY_PATH (linux) or DYLD_LIBRARY_PATH (mac os x).^[[0m
INFO: can not run systematics since can not link python to lhapdf

I had installed lhapdf6 using the install command in the shell of madgraph and am currently using VERSION 2.6.7.

Can you please help me in resolving this issue?

Thanks,
Disha

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Olivier Mattelaer
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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

I actually do not think that lhapdf5 is compatible with the systematics issue since as far as I known, python support started with lhapdf6.

Cheers,

Olivier

> On 1 Apr 2021, at 20:50, Disha Bhatia <email address hidden> wrote:
>
> New question #696351 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/696351
>
> Hi,
>
> I was trying to run the madgraph output to generate systematics to my process.
> However there is an error coming while running of madgraph and it is:
> Failed to access python version of LHAPDF: If the python interface to LHAPDF is available on your system, try adding its location to the PYTHONPATH environment variable and theLHAPDF library location to LD_LIBRARY_PATH (linux) or DYLD_LIBRARY_PATH (mac os x).^[[0m
> INFO: can not run systematics since can not link python to lhapdf
>
> I had installed lhapdf6 using the install command in the shell of madgraph and am currently using VERSION 2.6.7.
>
> Can you please help me in resolving this issue?
>
> Thanks,
> Disha
>
>
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Disha Bhatia (dishabhatia1989) said : 		#2

Actually I installed lhadpd6 only not version 5 but still it complained.

Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#3

Ok sorry, I read lhapdf5 not lhapdf6 (not sure why).

So what is your OS?
and how did you set
PYTHONPATH
and
LD_LIBRARY_PATH
(or DYLD_LIBRARY_PATH)

We do not update those value for you (even with the install command) however on some system (in particular ubuntu20), the os prevent us to update those value on the flight if they are not set correctly. If you use one of those os, we can not set those value in a way that make the link to lhapdf fully automatic (but if we would allow ourself to edit your ~/.bashrc like some program do, but this is a bad behavior)

Cheers,

Olivier

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Disha Bhatia (dishabhatia1989) said : 		#4

Thanks Olivier Mattelaer, that solved my question.

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Disha Bhatia (dishabhatia1989) said : 		#5

Thank you very much, I had not specified the paths in the bashrc, upon doing so now systematics are running fine.