simecol (version 0.6-6)

lv: Lotka-Volterra Predator-Prey Model

Description

simecol example: basic Lotka-Volterra predator prey-model.

Usage

data(lv)

Details

To see all details, please have a look into the implementation.

References

Lotka, A. J. 1925. Elements of physical biology. Williams and Wilkins, Baltimore.

Volterra, V. (1926). Variazionie fluttuazioni del numero d'individui in specie animali conviventi. Mem. Acad.Lincei, 2, 31-113.

See Also

simecol-package, sim, parms, init, times.

Examples

##============================================
## Basic Usage:
##   explore the example
##============================================
data(lv)
print(lv)
plot(sim(lv))

parms(lv) <- c(k1=0.5, k2=0.5, k3=0.5)
plot(sim(lv))

##============================================
## Implementation:
##   The code of the Lotka-Volterra-model
##============================================
lv <- new("odeModel",
  main = function (time, init, parms) {
    x <- init
    p <- parms
    dx1 <-   p["k1"] * x[1] - p["k2"] * x[1] * x[2]
    dx2 <- - p["k3"] * x[2] + p["k2"] * x[1] * x[2]
    list(c(dx1, dx2))
  },
  parms  = c(k1=0.2, k2=0.2, k3=0.2),
  times  = c(from=0, to=100, by=0.5),
  init   = c(prey=0.5, predator=1),
  solver = "rk4"
)