SSpquad3 {nlraa} | R Documentation |
self start for plateau-quadratic function
Description
Self starter for plateau-quadratic function with (three) parameters a (intercept), b (slope), c (quadratic)
Usage
pquad3(x, a, b, c)
SSpquad3(x, a, b, c)
Arguments
x |
input vector |
a |
the intercept |
b |
the slope |
c |
quadratic term |
Details
Reference for nonlinear regression Archontoulis and Miguez (2015) - (doi:10.2134/agronj2012.0506).
Value
a numeric vector of the same length as x containing parameter estimates for equation specified
quadp: vector of the same length as x using the quadratic-plateau function
Examples
require(ggplot2)
require(minpack.lm)
set.seed(123)
x <- 1:30
y <- pquad3(x, 20.5, 0.36, -0.012) + rnorm(30, 0, 0.3)
dat <- data.frame(x = x, y = y)
fit <- nlsLM(y ~ SSpquad3(x, a, b, c), data = dat)
## plot
ggplot(data = dat, aes(x = x, y = y)) +
geom_point() +
geom_line(aes(y = fitted(fit)))
[Package nlraa version 1.9.7 Index]