For each state k, the increase in occupation probability depends on the contribution from all other states to k, and is given by: ∑ ∑ ℓ ℓ A k ℓ ℓ P ℓ ℓ , where P ℓ ℓ is the probability for the system to be in the state ℓ ℓ , while the matrix A is filled with a grid of transition-rate constants. Similarly, P k contributes to the occupation of all other states P ℓ ℓ , ∑ ∑ ℓ ℓ A ℓ ℓ k P k ,