Individual-based model of population dynamics with movement of individual animals

Model : animal1
Simile version : 3.1+
Date added : 2003-06-20
Keywords : Individual-based ; Population dynamics ; Movement ;

Description

This models the dynamics of a population of animals, represented as a set of individuals that come into existence, live for a while, then die. When the animals are alive, they move around according to a simple random walk.

Files

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animal1.sml

Diagram

Equations

Equations in Desktop
	N = sum({one})
	
	Equations in ANIMAL
	X:    initial value = rand(30,70)
	Y:    initial value = rand(30,70)
	Dir:  initial value = rand(0,6.28)

	create = 100
	r = rand(0,2*0.7)
	m = 0.6

	xchange = (if outside == 1 then speed*cos(dir+3.14) else speed*cos(dir))
	dirchange = (if outside == 1 then 3.14/dt(1) else rand(-0.4,0.4)/dt(1))
	ychange = (if outside == 1 then speed*sin(dir+3.14) else speed*sin(dir))

	speed = 5
	size = 3
	outside = (if (x<0;x>100;y<0;y>100)then 1 else 0)
	one = 1

Results

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