Simple Hybrid Tree

A SimpleHybridTree is a tree that is split into two parts: an upper tree and a lower tree. The upper tree spans the levels from minlevel to hybridlevel, while the lower tree spans the levels from hybridlevel+1 to maxlevel. This allows the 𝓗² Method to treat both parts of the tree differently.

A SimpleHybridTree can be constructed from a TwoNTree with a SimpleHybridTreeBuilder. The hybridhalfsize determines the level at which the tree is split.

In the Galerkin case, a hybrid TwoNTree can be constructed as follows:

m = meshsphere(1.0, 0.1)
tree = SimpleHybridTree(
    TwoNTree(vertices(m); builder=TwoNTreeBuilder(; minhalfsize=0.1, minvalues=0));
    builder=SimpleHybridTreeBuilder(; hybridhalfsize=0.2),
)

TwoNTree{3,Float64}
level   nodes         avg values    avg children  halfsize      
1       1             1610.0        8.0           1.6           
2       8             201.25        4.0           0.8           
3       32            50.31         3.41          0.4           
4       109           14.77         3.3           0.2           
5       360           4.47          0.0           0.1           
upper levels start at: 3

Translating plans can be split into two with the splitplan function.