knife edge ogive

A method to simulate a knife edge ogive where at a given age the proportion chnages from 0 to 1

# S4 method for FLQuant,FLPar
knife(age, params, ...)

Arguments

age

FLQuant, FLPar or numeric with ages

params

FLPar

...

any other arguments

Value

returns an object of same type as age e.g. FLQuant

Details

The knife ogive is an S-shaped or knife curve or knifeal functions, Verhulst hypothesizes that small populations increase geometrically, because the supply of resources exceeds demand. Then, as supply and demand balance, population growth is constant. Finally, as demand exceeds supply, population growth decreases at the same rate that it had increased. Verhulst describes this process with an equation that enables him to predict when a population will reach any given size (see Verhulst's Figure):

See also

sigmoid, dnormal, logistic

Examples

if (FALSE) {
params=FLPar(a1=4)
age=FLQuant(1:10,dimnames=list(age=1:10))
knife(age,params)
}