Tracking: private API

PortfolioOptimisers.VariableTrackingType
abstract type VariableTracking <: AbstractAlgorithm

Abstract supertype for all variable-based tracking formulation algorithms.

A variable tracking algorithm states which quantity a risk-tracking measure compares against its benchmark: the weights that go into the risk measure, or the risk that comes out of it. It is orthogonal to the norm that measures the comparison, which a tracking measure holds in a separate field as a NormError.

All concrete and/or abstract types representing variable-based tracking algorithms should be subtypes of VariableTracking.

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PortfolioOptimisers.narrow_optimiser_vectorFunction
narrow_optimiser_vector(opti::AbstractVector) -> Any

Narrow a vector of optimisers so element-level TimeDependent schedules type-check.

A literal like [MeanRisk(), TimeDependent(…)] infers eltype AbstractEstimator, which the VecOptE_Opt_TD bound rejects even though every element is admissible. Vectors already matching the bound pass through unchanged; otherwise every element is checked against OptE_Opt_TD and the vector is rebuilt with the tightest element-type union. A field-level schedule passes through untouched.

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