grofit (version 1.1.1-1)

gompertz.exp: Modified Gompertz growth law

Description

The function calculates the values of the modified Gompertz growth curve for given time points.

Usage

gompertz.exp(time, A, mu, lambda, addpar)

Arguments

time

Time points (x-axes) for which the function values will be returned

A

Maximum of the curve. If a vector is provided only the first entry is used.

mu

Maximum slope. If a vector is provided only the first entry is used.

lambda

Lag-phase. If a vector is provided only the first entry is used.

addpar

Numeric vector of size two, addpar[1] corresponds to scaling parameter $\alpha$ and addpar[2] corresponds to shifting parameter $t_{shift}$.

Value

Numeric vector giving the values of modified Gompertz growth law for numeric input vector time.

Details

The function follows the parametrization $$y(t)=A\cdot \exp [-\exp (\frac{\mu \cdot \exp (1)}{A}(\lambda -t)+1)]+A\cdot \exp (\alpha (t-t_{shift}))$$

Examples

x <- 1:30
y <- gompertz.exp(x, 10, 2, 5, c(1,2))
plot(x,y)