Simulating posum data {posum}R Documentation

Population Surface Model Simulation

Description

These routines are for numerically integrating the McKendrick equation to obtain population per unit age interval from the per capita death rates and recruitment rates specified in rec and pcdr. survival(a,t) finds the proportion surviving from birth to age a, t, while population(a,t) finds the populaiton per unit age interval at a, t using rec and survival.

Usage

survival(a,t)

population(a,t)

Arguments

a age survived to or at which population is required.
t time survived to or at which population is required.

Details

Survival is the negative exponential of the integral of per capiat death rate from recruitment to a, t. The integral is performed numerically using the trapezoidal rule. The population per unit age interval at a,t is just the product of the recruitment rate at t-a and the survival to a, t. Note that these functions do not operate on arrays.

Value

Returns the proportion surviving, or the population per unit age interval.

WARNING

Author(s)

Simon N. Wood snw@st-and.ac.uk

References

http://www.ruwpa.st-and.ac.uk/simon.html

See Also

death.surface, pcdr, population.data, population.surface, rec, sim.age.bound,

Examples

m<-30;a1<-30;t1<-100
pop<-matrix(0,m,m)
da<-a1/(m-1);dt<-t1/(m-1)
t<-a<-0:(m-1);a<-a*da;t<-t*dt
for (i in 1:m) for (j in 1:m) pop[i,j]<-population(a[i],t[j])
contour(a,t,pop,xlab="a",ylab="t") 

[Package Contents]