Author jfeist
1 Star
Updated Last
1 Year Ago
Started In
October 2019


Stable Dev Build Status Codecov

This package provides some tools to efficiently store arrays with exchange symmetries, i.e., arrays where exchanging two indices leaves the value unchanged. It stores the underlying data in a flat vector and provides mappings that allow to address it as a "normal" AbstractArray{T,N}. To generate a new one with undefined data, use

S = SymArray{Nsyms,T}(dims...)

where NSyms is a tuple that indicates the size of each group of exchangeable indices (which have to be adjacent for simplicity), T is the element type (e.g., Float64 or ComplexF64), and dims are the dimensions of the array (which have to fulfill length(dims)==sum(Nsyms). As an example

S = SymArray{(3,1,2,1),Float64}(10,10,10,3,50,50,50)

declares an array S[(i,j,k),l,(m,n),o] where any permutation of (i,j,k) leaves the value unchanged, as does any permutation of (m,n). Note that interchangeable indices obviously have to have the same size.


  • Allow specification and treatment of Hermitian indices, where any permutation conjugates the result (possibly only for 2 indices at a time?).

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