temporal.jl

"""
    TemporallyVariableUpdater{D,S} <: NeutralLandscapeUpdater

A `NeutralLandscapeUpdater` that has a prescribed level of temporal variation
(`variability`) and rate of change (`rate`), but no spatial correlation in where
change is distributed.
"""
@kwdef struct TemporallyVariableUpdater{D,R,V} <: NeutralLandscapeUpdater
    spatialupdater::D = missing
    rate::R = 0.1
    variability::V = 0.1
end

"""
    _update(tvu::TemporallyVariableUpdater, mat)

Updates `mat` using temporally autocorrelated change, using the direction and
rate parameters from `tvu`.

TODO: this doesn't have to be a Normal distribution, could be arbitrary
distribution that is continuous and can have mean 0 (or that can be transformed
to have mean 0)
"""
function _update(tvu::TemporallyVariableUpdater, mat)
    U = rand(Normal(0, variability(tvu)), size(mat))
    Δ = rate(tvu) .+ U
    mat .+ Δ
end