Exemple

1.                               a=0.01 # external factor

2.                               b=0.001 # internal factor

3.                               ycum=0

4.                               y<-rep(0,20)

5.                               for(i in 2:20){

6.                               y[i]<-(a+b*y[i-1])*(1000-ycum)

7.                               ycum=ycum+y[i]

8.                               }

9.                               y

10.                             matplot(1:20, y, pch = 1:1, type = "o", col = 1:1,xlab="Valeurs de x", ylab="Ventes et/ou Profits")