improve math in broken-line fit [12.0.x]

[fwyzard]

PR description:

Backport #35128 to CMSSW 12.0.x.

PR validation:

These changes fix the crash observed during CRuZeT run 344679.

If this PR is a backport please specify the original PR and why you need to backport that PR:

Backport of #35128

[fwyzard]

backport #35128

[fwyzard]

type bugfix

[fwyzard]

please test

[cmsbuild]

A new Pull Request was created by @fwyzard (Andrea Bocci) for CMSSW_12_0_X.

It involves the following packages:

• RecoPixelVertexing/PixelTrackFitting (reconstruction)

@jpata, @cmsbuild, @slava77 can you please review it and eventually sign? Thanks.
@felicepantaleo, @GiacomoSguazzoni, @JanFSchulte, @rovere, @VinInn, @mmusich, @mtosi, @dgulhan this is something you requested to watch as well.
@perrotta, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

• Backported from improve math in broken-line fit #35128

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-1cbcd7/18678/summary.html
COMMIT: 477e2c8
CMSSW: CMSSW_12_0_X_2021-09-16-1100/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/35313/18678/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 2805 differences found in the comparisons
• DQMHistoTests: Total files compared: 39
• DQMHistoTests: Total histograms compared: 2998564
• DQMHistoTests: Total failures: 4120
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2994422
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 38 files compared)
• Checked 165 log files, 37 edm output root files, 39 DQM output files
• TriggerResults: found differences in 1 / 38 workflows

[slava77]

Reco comparison results: 2805 differences found in the comparisons

these are all in 11634.911 DD4HEP, which has repeatability issues

[slava77]

+reconstruction

for #35313 477e2c8

• code changes are the same as in the master PR improve math in broken-line fit #35128 , which was merged for about 2 weeks already ==> the backport is correct
• jenkins tests pass and comparisons with the baseline show no relevant differences

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_12_0_X IBs (tests are also fine) and once validation in the development release cycle CMSSW_12_1_X is complete. This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

@slava77 the description of the master version of this PR says "Expect some negligible differences (present even in the unit test)".
They are just possible numerical-level differences, as far as I understand: does it comply with the no-change rule that we must apply now for 12_0_X, for which productions have started already?

[fwyzard]

@perrotta I don't think the Patatrack pixel tracking is used anywhere in production, yet.
It's enabled only by the .501, .502, .505 and .506 workflows.

[perrotta]

@perrotta I don't think the Patatrack pixel tracking is used anywhere in production, yet.
It's enabled only by the .501, .502, .505 and .506 workflows.

Good point :-)

[perrotta]

+1