geometry precision errors

Dear FLUKA authors and users,

I have got two questions related with problems with a precision in geometry.

1. Precision errors on boundary.

I have defined a base cell using RPP declaration, but my lattice cells, being rotating of this last one, are decalred with PLA declaration,
could I have some problems related with this?

I am asking because I am trying to
debug a geometry.

When I hit my geometry with PHOTON BEAM (momentum = 10 GeV/c) I get the following error message:

---------------------
"error messsage"

NEXT SEEDS: 12AF7A 0 0 0 0 0 181CD 3039 0 0
Geofar: Particle in region 2 (cell # 0) in position 2.499620401E+01 -1.121151881E+01 1.530000000E-03
  is now causing trouble, requesting a step of 1.000000000E+08 cm
  to direction -8.540679798E-02 -7.081037323E-01 -7.009242350E-01, error count: 0
  R2: 2.739540781E+01 R3: 2.739540785E+01 cm
  X*U (2D): 5.804072569E+00 X*U (3D): 5.803000155E+00 cm
  X*UOLD(2D): -9.155329813E+00 X*UOLD(3D): -9.154151914E+00 cm
  Kloop: 81377, Irsave: 591, Irsav2: 2, error code: -33 Nfrom: 5000
  old direction -5.274356424E-01 -3.593232260E-01 7.698691203E-01, lagain, lstnew, lsense, lsnsct F F F F
  Particle index 7 total energy 5.780450824E-03 GeV Nsurf16253
Try again to establish the current region moving the particle of a 1.000000000E-06 long step
We succeeded in saving the particle: current region is n. 2 (cell # 0)
---------------------

This point is exactly on boundary, and I read in Fluka manual that this is related with "a rounding error near a boundary",

but when I hit at the same point with MUON+ BEAM (momentum = 10 GeV/c) everything is correct and I saw normal energy deposits.

I built my geometry with precision 15 digits after dot. Geometry debugger tels "no errors in geometry file" for this point.
And I am able to make visualization all my geometry with FLAIR.
In lattic.f I use a rotation subroutine with double precision.

I know a similar problems were discussed before:
http://www.fluka.org/web_archive/earchive/new-fluka-discuss/0045.html

2. What(2) geobegin card.

I read too that it is possible to modify an accuracy of the geometry using WHAT(2) command in GEOBEGIN card.
But I don't know how I can change this precision and if this is safe solution.

 
Thanks for help,

Best greetings,
jaroslaw

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Forschungszentrum Juelich GmbH
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Vorsitzende des Aufsichtsrats: MinDir'in Baerbel Brumme-Bothe
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Dr. Ulrich Krafft (stellv. Vorsitzender), Prof. Dr. Harald Bolt,
Dr. Sebastian M. Schmidt
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Received on Sun Apr 6 16:02:38 2008