Re: Which Rotation class?

Hi Denis,
I did not wanted to have TGeo bound to the matrix package because it has to handle only space vectors and rotation matrices. On the other hand, I fully agree that an interface to allow using TMatrix and TVector objects with TGeo is highly desirable - unfortunately not much manpower to do that. Cheers,
Andrei

Bertini, Denis Dr. wrote:
>
> Hello ,
>
> I would like to understand the situation with the basic Linear Algebra
> in ROOT since
> it is rather confusing to me.
>
> First for the ROOT navigation system one has to use TGeoRotation. Fine
> for me , but
> in which representation are these Rotations ? What is the SetAngles()
> underlying representation.?
> Why is there no overloaded operators "*" or "+"?
> Why is there no connection via a "*" overloaded operator to a simple
> TVector3 ?
>
> In wich order should i do a multiple matrix multiplication ?
> MULT = A * B * C
> It seems not clear to me !
>
> Now there is another Rotation that one can use TRotation but to jump
> from TGeoRotation
> to this one i need a constructor
> ::TRotation(Double_t xx, Double_t xy etc ..)
>
> which is not protected !
>
> Then another choice from ROOT library ( actually i choose this one )
> there is the Rotation3D
> from the math library. Once again what is the represention. Of course
> it differs from TGeoRotation
> to Rotation3D, why ?
>
> Then there is no connection between TVector3 and this Matrix class ,
> one has to go to another representation
> again XYZPoint in order to do a simple vector transformation T' = MAT
> * T. Why that ?
> And why is there not "+" overloaded operator for the XYZPoint ?
>
> All that is rather confusing to me, it seems that everything is
> developped independently ... Is there here
> a chance to have in the future something more unifyied ?
>
> Best Regards,
>
> Denis Bertini
>
>
Received on Thu Jul 23 2009 - 11:00:59 CEST