Re: Geometry expansion statement

From: Vittorio Boccone <>
Date: Mon, 18 Jun 2012 12:24:48 +0200

Dear Chris,
    I agree manual need to be clarified a bit.

The application of the scaling matrix to the expansion is shown (for
example) in the slides of the JLab course

8.4.4} Geometry directives: usage notes
   Directives $Start_expansion and $Start_translat are applied when reading
   the geometry: therefore they imply no CPU penalty. Directive
   $Start_transform, instead, is applied at run-time and requires some
   additional CPU time.

-> Run time matrix transformation is used only for $Start_transform.


On 17/06/2012 15:31, Chris Theis wrote:
> Dear colleagues,
> I was recently looking into some geometry statements of FLUKA and there is some contradiction in the manual regarding the
> $start_expansion statement for which I would appreciate some clarification.
> The manual states that the statement provides the expansion/reduction of body dimensions, whereas the example given suggests that
> actually a scaling matrix is applied to the object instead of a true expansion, which is applicable to the object's dimensions only
> and not to the object's position.
> I would appreciate if somebody could comment what the code is actually doing in this case.
> Thanks a lot
> Chris

Dr. Vittorio Boccone - University of Geneva
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Received on Mon Jun 18 2012 - 20:30:55 CEST

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