syten::Krylov::OrthoPolicies Namespace Reference

Orthonormalisation policies used by StandardKrylov and TensorNetworksKrylov. More...

Classes
struct	AllButLast
	Orthogonalises only against the first N-2 vectors of the set of size N, i.e. More...
struct	Arithmetic
	Arithmetic orthonormalisation. More...
struct	Combined
	Uses two different implementations to first orthonormalise against the last two vectors of the orthogonalisation set and then against all vectors of that set. More...
struct	Complete
	Completely orthogonalises the space using the specified OrthoImpl class method. More...
struct	LastTwo
	Orthogonalises only against the last two vectors of the orthogonalisation set. More...
struct	None
	Does nothing when called to orthonormalise or orthogonalise(). More...
struct	TwoSiteVariational
	Two-site variational orthonormalisation. More...
struct	Variational
	Variational orthonormalisation. More...

Detailed Description

Orthonormalisation policies used by StandardKrylov and TensorNetworksKrylov.

The interface provided by the completed policy classes are:

• the orthonormalise() function which takes the desired vector, a vector of vectors against which to orthonormalise, the iterative config to use and the iterative exit object to encode the return value.
• the orthogonalise() function which orthogonalises but does not orthonormalise.
• the invSubspaceSufficient() function which returns true if the orthogonalisation procedure is such that a resulting zero norm is only due to actual linear dependence and not other effects such as a limited variational space. In other words, if this function returns true, encountering an invariant subspace within Krylov implies that the problem was solved exactly.