# SSasympOrig {stats}

### Description

This `selfStart`

model evaluates the asymptotic regression function through the origin and its gradient. It has an `initial`

attribute that will evaluate initial estimates of the parameters `Asym`

and `lrc`

for a given set of data.

### Usage

SSasympOrig(input, Asym, lrc)

### Arguments

- input
- a numeric vector of values at which to evaluate the model.
- Asym
- a numeric parameter representing the horizontal asymptote.
- lrc
- a numeric parameter representing the natural logarithm of the rate constant.

### Values

a numeric vector of the same length as `input`

. It is the value of the expression `Asym*(1 - exp(-exp(lrc)*input))`

. If all of the arguments `Asym`

and `lrc`

are names of objects, the gradient matrix with respect to these names is attached as an attribute named `gradient`

.

### Examples

Lob.329 <- Loblolly[ Loblolly$Seed == "329", ] SSasympOrig(Lob.329$age, 100, -3.2) # response only Asym <- 100; lrc <- -3.2 SSasympOrig(Lob.329$age, Asym, lrc) # response and gradient getInitial(height ~ SSasympOrig(age, Asym, lrc), data = Lob.329) ## Initial values are in fact the converged values fm1 <- nls(height ~ SSasympOrig(age, Asym, lrc), data = Lob.329) summary(fm1)

Documentation reproduced from R 3.0.2. License: GPL-2.