Solves a pairwise approximation to the SIS model on a random network of N individuals, each with n contacts.
time sequence for which output is wanted; the first value of times must be the initial time.
further arguments passed to ode function.
This is the R version of program 7.8 from page 285 of "Modeling Infectious Disease in humans and animals" by Keeling & Rohani.
All parameters must be positive.
list. The first element,
*$model, is the model function. The second, third and fourth elements are the vectors
*$time, containing the
time arguments of the function. The fifth element
*$results is a
data.frame with up to as many rows as elements in time. First column contains the time. Second, third and fourth columns contain the number of susceptibles, infectious and susceptible-infectious pairs.
Keeling, Matt J., and Pejman Rohani. Modeling infectious diseases in humans and animals. Princeton University Press, 2008. Modeling Infectious Diseases in Humans and Animals
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# Parameters and initial conditions. n <- 4; N <- 1e4; Y <- 1; X <- N - Y parameters <- c(tau = 0.1, gamma = 0.05, n = n, N = N) initials <- c(X = X, Y = Y, XY = n * Y * X / N) # Solve and plot. sis.pairwise.approx <- SISPairwiseApprox(pars = parameters, init = initials, time = 0:100) PlotMods(sis.pairwise.approx)
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