Metapopulation SEIR model This code combines two deterministic metapopulation SEIR models as described in [Lloyd Jansen ()](https://doi.org/./j.mbs...). Cross-coupling between patches Equations Cross-coupling is controlled through matrix Beta describing the effective contact rates acting within and between patches. Setting the off-diagonal elements of Beta to zero, we switch off cross-coupling across patches. Migration between patches Equations Matrix C must be such that the elements on the diagonal, denoting outflow of each patch, are negative. Element C_ij describes the flow from patch I to patch J For each row, the sum all elements on the row is Setting all elements of C to zero, we switch off migration between patches. Model description This model consists of many SEIR models connected through between-patch contact and/or migration of individuals between patches. The model has a constant total population size, which means that births and deaths correspond at each time step. N number of patches S_, S_n susceptibles in patches n E_, E_n exposed in patches n I_, I_n infectious in patches n R_, R_n recovered in patches n Beta_ij effective contact rate of infected individuals of patch I to susceptible individuals of patch J C_ii outflow of patch I c_{ij}, i neq j flow from patch I to patch J Sigma rate of breakdown to active (and infectious) disease Gamma rate of recovery from active disease Mu background mortality/birth rate The model will be written as