Schnute {FSA} R Documentation

## The four-parameter growth function from Schnute (1981).

### Description

The four-parameter growth function from Schnute (1981).

### Usage

```Schnute(
t,
case = 1,
t1 = NULL,
t3 = NULL,
L1 = NULL,
L3 = NULL,
a = NULL,
b = NULL
)
```

### Arguments

 `t` A numeric vector of ages over which to model growth. `case` A string that indicates the case of the Schnute growth function to use. `t1` The (young) age that corresponds to `L1`. Set to minimum value in `t` by default. `t3` The (old) age that corresponds to `L3`. Set to maximum value in `t` by default. `L1` The mean size/length at `t1`. `L3` The mean size/length at `t3`. `a` A dimensionless parameter that is related to the time/age at the inflection point. `b` A dimensionless parameter that is related to size/length at the inflection point.

### Value

`Schnute` returns a predicted size given the case of the function and the provided parameter values.

### IFAR Chapter

None specifically, but 12-Individual Growth is related.

### Author(s)

Derek H. Ogle, derek@derekogle.com

### References

Schnute, J. 1981. A versatile growth model with statistical stable parameters. Canadian Journal of Fisheries and Aquatic Sciences 38:1128-1140.

See `vbFuns`, `GompertzFuns`, `RichardsFuns`, `logisticFuns`, and `SchnuteRichards` for similar functionality for other models.

### Examples

```## See the formulae
growthFunShow("Schnute",1,plot=TRUE)
growthFunShow("Schnute",2,plot=TRUE)
growthFunShow("Schnute",3,plot=TRUE)
growthFunShow("Schnute",4,plot=TRUE)

## Simple examples
ages <- 1:15
s1 <- Schnute(ages,case=1,t1=1,t3=15,L1=30,L3=400,a=0.3,b=1)
s2 <- Schnute(ages,case=2,t1=1,t3=15,L1=30,L3=400,a=0.3,b=1)
s3 <- Schnute(ages,case=3,t1=1,t3=15,L1=30,L3=400,a=0.3,b=1)
s4 <- Schnute(ages,case=4,t1=1,t3=15,L1=30,L3=400,a=0.3,b=1)

plot(s1~ages,type="l",lwd=2)
lines(s2~ages,lwd=2,col="red")
lines(s3~ages,lwd=2,col="blue")
lines(s4~ages,lwd=2,col="green")

```

[Package FSA version 0.8.26.9000 Index]