MadonnaModelø Arialþ!þþDþö(.2> B 6:9B­ ø¥{Rosenzweig-MacArthur 1963 Resource/consumer or Prey/Predator model} {From Turchin, 2003, p. 46} {simulation control block} STARTTIME = 0 STOPTIME=200 DT = 0.01 {number of prey or resources} N(t) = N(t - dt) + (dNdt) * dt INIT N = InitN dNdt = (r0*(1-N/K))-Resource_use {number of predators or consumers} P(t) = P(t - dt) + (dPdt) * dt INIT P = InitP dPdt = (chi*Resource_use)-(gamma*P) {resource use -- number of prey or resources consumed} Resource_use = (c*N*P)/(d+N) {parameters} InitN = 50 {initial number of prey or resources} {to be set by external file} InitP = 10 {initial number of predators or consumers} {to be set by external file} K = 125 {carrying capacity of environment for prey or resources} {to be set by external file} r0 = .75 {fraction of prey produced per capita in a limitless environment} c = .50 {fractions of prey-predator interactions that result in consumption} d = 50 {scaling factor to show how per capita consumption decays with density} chi = 3 {number of predators produced per prey consumed} gamma = .50 {death fraction for predators in the absence of prey} øöéöø9@ørk4ööþöúü©ñÒMbP?úü©ñÒMbP?ööúü©ñÒMbP?   DHL &,2^.Fjnr z avñáÍ=5 !$¥&­(µ*½,E.YÅ