The rational function SAR regression model

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Description

S == (c + z * A) / (1 + f * A)

Usage

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Format

The format is: List of 8 $ name : "Rational function" $ formula : expression(S == over((c + z * A), (1 + f * A))) $ paramnumber: 3 $ paramnames : "c" "z" "f" $ parLim : "R" "R" "R" $ fun : model function $ rssfun : Residual Sum of Squares function $ init : initial values calculation $ form : a formula object for further calculations

Details

The rational function model (Ratkowsky, 1990) is convex asymptotic. Each parameter in the model affects several curve aspects (shape, upper asymptote and y-axis intersection).

Source

Ratkowsky (1990), Tjørve (2003).

References

Ratkowsky, D.A. (1990) Handbook of nonlinear regression models. Marcel Dekker, New York.

Tjørve, E. (2003) Shapes and functions of species–area curves: a review of possible models. Journal of Biogeography, 30, 827–835.

Examples

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#loading the ratio model object before using it
data(ratio)