#Example 1

volrec=function (x,y,z)
{
	vol=x*y*z
	return(vol)
	
}

#Example 2

ricker=function(nzero, r, K=1, time=100, from=0, to=time)
{
	N=numeric(time+1)
	N[1]=nzero
	for (i in 1:time) N[i+1]=N[i]*exp(r*(1-N[i]/K))
	Time=0:time
	plot(Time, N,type="l",xlim=c(from,to))	
}

layout(matrix(1:3,3,1))
ricker(0.1,1);title("r = 1")
ricker(0.1,2);title("r = 2")
ricker(0.1,3);title("r = 3")