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christopherpoole / G4VoxelData

A generic voxelised data loader for GEANT4.
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G4VoxelDataParameterisation::ComputeMaterial for z == -1 #15

Open janpipek opened 10 years ago

janpipek commented 10 years ago

Dear Christopher,

this is more a question than an issue. However, I see that you have observed Geant4 calling %subj% method with negative replica number (on line 157 you deal with it) . Do you know whether this is a known bug of Geant4 (possibly round-off errors with boundaries)?

I am developing a DICOM handling library and when testing, once in a few thousand z=0 boundary crossings, this situation appears too.

Thanks, Jan

christopherpoole commented 10 years ago

Hi Jan,

I don't think it is a bug, but it is something I have never figured out properly. It could be down to floating point precision/rounding and the navigator not actually being able to determine if it is on a boundary or not. It happens rarely and only in parametrised volumes it seems. At the moment I am pretending it isn't happening.

I might look into it further now that you have mentioned it.

Chris.

On 17 May 2014 23:03, Jan Pipek notifications@github.com wrote:

Dear Christopher,

this is more a question than an issue. However, I see that you have observed Geant4 calling %subj% method with negative replica number (on line 157 you deal with it) . Do you know whether this is a known bug of Geant4 (possibly round-off errors with boundaries)?

I am developing a DICOM handling library and when testing, once in a few thousand z=0 boundary crossings, this situation appears too.

Thanks, Jan

— Reply to this email directly or view it on GitHubhttps://github.com/christopherpoole/G4VoxelData/issues/15 .