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None G4MagIntegratorDriver::OneGoodStep error 

Forum: Fields: Magnetic and Otherwise
Date: 13 Jun, 2005
From: John Carter <John Carter>

Hi all,

I'm having problems with a user-defined solenoid field. I have set up the
field and tested it with a few dry runs and it seems to work ok. However, 
some events produce the following 'error' output:

G4MagIntegratorDriver::OneGoodStep: Stepsize underflow in Stepper 
  Step's start x=16376 and end x= 16376 are equal !! 
  Due to step-size= 2.5e-13 . Note that input step was 2.5e-06

This is something that randomly happens and I call it an 'error' because it
doesn't cause the program to crash, merely locks it up. I have tried changing 
my MaxAllowedStep for my volume and I don't seem to get the error if I reduce
the step length to something on the order of 10mm. However, this vastly reduces
the speed of the tracking (18 hours to track 1000 events compared to a few seconds...)

Has anyone seen this error and know the cause or a workaround?



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1 None: Re: G4MagIntegratorDriver::OneGoodStep error   (John - 14 Jun, 2005)
(_ None: Re: G4MagIntegratorDriver::OneGoodStep error   (Tom Roberts - 21 Jun, 2005)
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