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madgraph5 / madgraph4gpu

GPU development for the Madgraph5_aMC@NLO event generator software package
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master_june24: xsec mismatch in ggttggg for FPTYPE=f (must increase tolerance) #889

Closed valassi closed 5 days ago

valassi commented 5 days ago

Another issue which appeared through #830 and being reviewed in #882.

In WIP PR #882 I added a workaround (NOT a fix) for crash #885 just to allow the CI tests to proceed further. Apart from other 'expected' failures, there is a xsec mismatch for ggttggg. This can be fixed by increasing tolerance https://github.com/madgraph5/madgraph4gpu/actions/runs/9807713341/job/27082079782

*** (2-sse4) Compare MADEVENT_CPP xQUICK xsec to MADEVENT_FORTRAN xsec ***

ERROR! xsec from fortran (2.6007004181875136E-006) and cpp (2.6020625819045072E-006) differ by more than 4E-4 (0.0005237680232093034)
valassi commented 5 days ago

I increased it to 6E-4. Enough for sse4, not enough for avx2...

https://github.com/madgraph5/madgraph4gpu/actions/runs/9807953772/job/27082866125#step:12:112

*** (2-avx2) Compare MADEVENT_CPP xQUICK xsec to MADEVENT_FORTRAN xsec ***

ERROR! xsec from fortran (2.6007004181875136E-006) and cpp (2.6034626920972927E-006) differ by more than 6E-4 (0.001062126914142647)
valassi commented 5 days ago

Ok fixed in #882 (for the master_june24 branch, to be merged there eventually). Closing.

PS I also immediately merged the patch into master in #890.