kappa4alShort: Sigmoidal curve fitting.

In alR: Arc Lengths of Statistical Functions

Description

A framework for arc length fitting of the four-parameter kappa sigmoidal function.

Usage

kappa4alShort(formula, data = list(), xin, q1, q2, ...)

Arguments

formula	An LHS ~ RHS formula, specifying the linear model to be estimated.
data	A data.frame which contains the variables in formula.
xin	Numeric vector of length 3 containing initial values, for σ, h, and k.
q1, q2	Numeric vectors, for the lower and upper bounds of the intervals over which arc lengths are to be computed.
...	Arguments to be passed on to the outer control list of constrOptim.nl.

Details

A shortened version of kappa4al.

Value

kappa4alShort: A list with the following components:

• coefficients: A vector of estimated coefficients.

• error: The value of the objective function.

Examples

k <- kappa4tc(-4, 0, 1)$par
x <- seq(qkappa4(0, 4, 0.4, -4, k), qkappa4(0.7, 4, 0.4, -4, k), length.out=100)
y <- sapply(x, function(i) pkappa4(i, 4, 0.4, -4, k))
kappa4alShort(y~x, xin=c(0.1, -3, -0.1), q1=c(0.1, 0.5), q2=c(0.5, 0.9))

alR documentation built on Dec. 7, 2017, 5:03 p.m.