Tim Adye

> I don't think the magnetic field interpolation should fail silently in this way, to be honest. `InterpolatedBFieldMap` defines underflow and overflow bins, so there is a clear definition for...

> Got it, it's here #784 and then I introduced this error mode in #825. > I also had some discussion with @HadrienG2 about this in #821. Sorry, I didn't...

Hi @CouthuresJeremy, Thanks for checking this. That is very useful. I didn't do an exact comparison between the C++ and Python implementations, just checking the distributions. I did do some...

Just to confirm, I see the same effect that @CouthuresJeremy described (using #1174). And using `preselectParticles=False` makes no difference. Sorry, that doesn't add anything to @CouthuresJeremy's observation.

One idea... We have the same input particle, and Fatras makes small changes to the output particile. So I guess it's different multiple scattering or energy loss. A real difference...

I see #1454 has been merged. Thanks! Unfortunately I get as many ```TrackFinding ERROR Step failed with MagneticFieldError:1: Interpolation out of bounds was requested``` errors as before.

Moving the discussion from PR #1251 here: > This looks like the same issue. We don't see such a bad effect for the ATLAS B-field as sPHENIX do, but they...

> This looks to me like an off-by-one error due to the fact that we're using the lower left corner of the grid cells as the interpolation points. Yes, that...

reopened, until @osbornjd can see if #1381 fixes the original issue.

This is a blocker for me :( Ctrl-Shift-Minus is also undo key for bash. Ctrl-X Ctrl-U can also be used, but is problematic as Ctrl-U on its own removes the...