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Adding protection for straight MFT tracks, to prevent divison by zero#7762

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jgrosseo merged 3 commits intoAliceO2Group:devfrom
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Dec 3, 2021
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Adding protection for straight MFT tracks, to prevent divison by zero#7762
jgrosseo merged 3 commits intoAliceO2Group:devfrom
sarahherrmann:branchSarah

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@sarahherrmann sarahherrmann commented Nov 29, 2021

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@sarahherrmann sarahherrmann requested a review from a team as a code owner November 29, 2021 13:09
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ktf reviewed Dec 2, 2021
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@jgrosseo and @aalkin should probably comment, but shouldn't we just avoid the division in that case and multiply by the provided 1/Pt? Where is this used?

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jgrosseo commented Dec 2, 2021

This is in principle fine. Of course alternatively we could consider to fill 1/pt with a very large number for straight tracks instead of 0. What do you think about this?
Tagging also @rpezzi

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sarahherrmann commented Dec 2, 2021

Hi ! Anton and Rafael are actually already aware of this proposal of modification (they were the ones that suggested me to do that for MFT tracks), and I don't know for the provided 1/Pt question sorry

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rpezzi commented Dec 2, 2021

Hi, I am OK with the current implementation.

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jgrosseo commented Dec 2, 2021

OK, thanks.

Last question: did you try to use Almost0 instead of the hard-coded small float value? Is Almost0 too small? Do we need a second constant?

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sarahherrmann commented Dec 2, 2021

I didn't try Almost0, I didn't know it existed. I will try it

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rpezzi commented Dec 2, 2021

Indeed Almost0 is more appropriate. It is safe for a floating point division by Almost0:

1.f/o2::constants::math::Almost0
(float) 8.50709e+37f

@jgrosseo jgrosseo enabled auto-merge (squash) December 2, 2021 15:43
@jgrosseo jgrosseo merged commit 8f162c2 into AliceO2Group:dev Dec 3, 2021
hhillema pushed a commit to ezradlesser/AliceO2 that referenced this pull request Dec 9, 2021
@sarahherrmann @iravasen
Adding protection for straight MFT tracks, to prevent divison by zero (…
733d279 
…AliceO2Group#7762)
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