NaN in reco

[michaelmackenzie]

There can be NaN issues in reconstruction. An example case is in Mu2eKinKal/inc/KKFit.hh:makeStrawHits where

      auto ppos = ptraj.position3(htime);
      auto vel = ptraj.velocity(htime);

return undefined values. This leads to ptime being NaN and this can be passed into downstream reco, sometimes causing errors or segmentation faults such as in TrackerConditions/src/StrawDrift.cc:T2D due to undefined bin values.

An example instance of a NaN time (but no errors/faults):

# Process on-spill reco
#include "Production/JobConfig/reco/OnSpill.fcl"

source : {
  module_type : RootInput
  fileNames: [
    "xroot://fndca1.fnal.gov/pnfs/fnal.gov/usr/mu2e/tape/phy-sim/dig/mu2e/ensembleMDS2cMix1BBTriggerable/MDC2020ba_best_v1_3/art/0f/f3/dig.mu2e.ensembleMDS2cMix1BBTriggerable.MDC2020ba_best_v1_3.001201_00000001.art"
  ]
  firstEvent: 7660
  firstRun: 1201
  firstSubRun: 1
  maxEvents: 1
}

services.DbService.purpose: MDC2020_best
services.DbService.version: v1_3
services.DbService.verbose : 2

outputs.Output.fileName   : "mcs.user.test_hit_error.version.sequencer.art"

Hit index 566/568 isn't well defined:

        KKFit::makeStrawHits: Non-finite ptime for hit index 566 for collection size 568, hpos.z() = 1514.39, ppos.z() = -nan, vel.z() = -nan

(can be seen by adding this to above CAHint hint(ptime,htime); in KKFit.hh:

      if(!std::isfinite(ptime)) throw cet::exception("RECO") << "KKFit::" << __func__
                                                             << ": Non-finite ptime for hit index " << strawidx << " for collection size " << chcol.size()
                                                             << ", hpos.z() = " << hpos.Z() << ", ppos.z() = " << ppos.Z() << ", vel.z() = " << vel.Z()
                                                             << "\n";

)