richard {growthmodels}

Richard growth model

Description

Computes the Richard growth model and its inverse

y(t) = \frac{\alpha}{(1 + \beta exp(-k t))^{(1/m)}}

Usage

richard(t, alpha, beta, k, m)

richard.inverse(x, alpha, beta, k, m)

Arguments

t

time

alpha

upper asymptote

beta

growth range

k

growth rate

m

slope of growth

x

size

Author(s)

Daniel Rodriguez

References

D. Fekedulegn, M. Mac Siurtain, and J. Colbert, "Parameter estimation of nonlinear growth models in forestry," Silva Fennica, vol. 33, no. 4, pp. 327-336, 1999.

Examples

growth <- richard(0:10, 10, 0.5, 0.3, 0.5)

time <- richard.inverse(growth, 10, 0.5, 0.3, 0.5)