"""

Compare two vectors of elements using Base.isapprox for each element's
ray matrix (ABCD entries). Does consequently not consider one
discretization of element FreeSpace different from another, or one
realization of an imaging system from another as long as both achieve
(within tolerances) the same imaging.

!!! note
    The `atol` (absolute tolerance) parameter can be used but is
    typically nonsensical as it will be used for each of the
    ray matrix entries ABCD which usually differ vastly in magnitude.

"""
Base.isapprox(
    a::Vector{<:Element}, b::Vector{<:Element}; kwargs...
) = isapprox(RTM(a), RTM(b); kwargs...)

