I have an application where I need to convert between SVector<3> objects (for matrix algebra) and GenVector XYZVector objects (for geometric functions). I am currently doing that ‘by hand’, ie
using ROOT::Math::XYZVector;
typedef ROOT::Math::SVector<double,3> SVector3;
XYZVector gv1, gv2;
SVector3 sv1, sv2;
…
sv1 = SVector3(gv1.X(), gv1.Y(), gv1.Z());
gv2 = XYZVector(sv2[0],sv2[1],sv2[2]);
Is there a more elegant (less error-prone) way to perform these cross-constructions?
thanks, Dave
Unfortunately now it is not possible, three is not a different constructor taking a vector such as SVector. It was forseen, see line 118 of https://root.cern.ch/doc/master/GenVector_2DisplacementVector3D_8h_source.html
but never enabled, probably because in the past there were some issues with the CINT template code.
Now that you are asking, if you need it, I could re-enable that code
Hi Lorenzo,
Thanks for your response. I had a vague recollection of this being supported or at least documented in earlier code, I’m glad to see I wasn’t completely wrong. I think it would be useful to have this functionality, it will result in cleaner, less fragile user code covering a legitimate and common use case. I suggest throwing if the dimensions don’t match exactly. What about the other direction? Could GenVector support operator []? That would allow cross-construction of SVector.