genInit: Generate initial values for nls function

Description Usage Arguments Details Value Examples

View source: R/genInit.R

Description

Generate multiple initial vectors for the nls function in sgSEMp1().

Usage

1
genInit(bounds = list(a1 = c(-3, 3), a2 = c(-3, 3), a3 = c(-3, 3)), k = 50)

Arguments

bounds

a list of three vectors of length = 2. Each vector gives the upper and lower limits of an interval from which the initial values are randomly generated. The default values list(a1 = c(-3, 3), a2 = c(-3, 3), a3 = c(-3, 3)) sets limits of all three initial values to be (-3, 3).

k

a positive integer (default = 50). The number of initial vectors to generate.

Details

Currently the non-linearizable function included in sgSEMp1() is y = a + b * exp(c * x), where a, b and c are coefficients to be estimated. Thus, an initial vector contains three values. The random initial values are generated by a uniform distribution between the bounds.

Value

A data frame. Each column corresponds to a coefficient. Each row corresponds to a random initial vector.

Examples

1
genInit(list(a1 = c(0,2), a2 = c(4,5), a3 = c(-1, -0.5)), k = 20 )

gSEM documentation built on May 30, 2017, 2:59 a.m.