
1. representation of rational truncated hierarchical b-splines does not seem to work with gsTensorNurbsBasis<2> (i.e. having the weights on the basis)
   it does work with homogenenous coordinates (wx,wy,wz,w) and gsTensorBSplineBasis<2> (i.e. having the weights on the coefs)
   -> should .geoDim() be 3 and .coefDim() 4? what about .dim() (is that equal to 2, for e.g. gsTHBSpline2 because it is the number of tensor dimensions?)

2. controlNet (i.e. basis().connectivity(m_coefs)) for a rational thb spline. Have to convert coefs to (x,y,z) first.

3. binary serialization as alternative for xml serialization.

4. how does adaptive refinement work and can we also do adaptive coarsening?

5. what does transfer2 and coarsening_direct2 do?

6. what is the m_xmatrix used for?

7. how to get UV-mapping on a mesh as input for surface fitting?

8. is there a way to get the 'row' and 'column' indices of hierarchical grips? this will enable navigation in row-wise or column-wise fashion.