Maps Reference

DoubleBasis{Tb1<:AbstractBasis, Tb2<:AbstractBasis}

Basis for constructing transition matrix from one symmetry sector to another. Note that DoubleBasis can be used as the projector, meaning that it will ignore the symmetry violation. Therefore, extra care is needed when working with this basis.

Interpretation:

• B1 is the target basis,
• B2 is the source basis,
• dgt follows the current source-side representative as iteration proceeds.

symmetrizer(B::DoubleBasis)

Return the linear map from coordinates in B.B2 to coordinates in B.B1.

This is the special basis-only map associated with a DoubleBasis:

• if B.B2 is a less symmetric basis, it acts as a symmetrization / projection into the target sector B.B1;
• in the general case it returns the overlap map between the two basis embeddings in the full tensor-product basis.

The returned matrix has size size(B, 1) × size(B, 2).